KEF LSX wireless loudspeaker system Measurements

Sidebar 3: Measurements

I used DRA Labs' MLSSA system and a calibrated DPA 4006 microphone to measure the KEF LSX's frequency response in the farfield, and an Earthworks QTC-40 microphone for the nearfield responses. After I connected the Master LSX to my network, it checked with KEF that its firmware was up to date—it was (v.3.0). I then opened the Roon app on my iPad Mini and the speaker was recognized by Roon as "KEF LSX" and successfully handled data sampled up to 192kHz via the network. The KEF's volume control was active in Roon as well as in KEF's own Control app, which I used to select inputs. The Master has both analog and digital inputs and I performed most of the measurements using its analog Aux input, which appears to have an input impedance of 6.8k ohms. I repeated some testing via the speaker's optical S/PDIF digital input, which locked reliably to data with sample rates up to 96kHz. I checked with the KEF app how the speakers were set before I started the measurements: Desktop and Wall modes off; Treble Trim, 0dB (the range is ±2dB); Phase Correction, on; Bass Extension, Standard; Subwoofer Output: off (the control panel offers subwoofer polarity, gain, and low-pass frequency adjustments).

One problem reared its head when I began testing: Like the Kii Three loudspeaker, which we reviewed in September 2017 and which is also digitally corrected, there was a significant latency when the LSX was fed an analog signal. I usually set MLSSA to examine the first 10 milliseconds of the sound emitted by a speaker, but in this case all I got was background noise. I increased the time window to 100ms and there was the speaker's impulse response, at the 52ms mark. This means that, fed an analog signal, the LSX delays its output by about 48ms. Peculiarly, when fed S/PDIF digital data, the latency was a more manageable 5ms, which means there will be no synchronization problems when the KEFs are connected to a video player's optical digital output.

There is no convention for specifying the sensitivity of a powered speaker, but when I set the LSX's volume control to its maximum of "100" and fed the speaker's Aux input pink noise at 300mV, the resultant SPL was 90dB(C) at 1m on the tweeter axis. With pink noise at –20dBFS fed to the optical digital input, the SPL at 1m was the same 90dB(C). The enclosure seemed relatively inert with the knuckle-rap test, though when I investigated its vibrational behavior with a plastic-tape accelerometer I found a moderately strong resonant mode at 258Hz on the sidewalls (fig.1), and a higher-level mode at 727Hz on the top panel. While I could hear these modes through a stethoscope when playing a recording of a man speaking, they were inaudible at the listening position, presumably because of the small radiating areas of the affected surfaces.


Fig.1 KEF LSX, cumulative spectral-decay plot calculated from output of accelerometer fastened to center of sidewall (MLS driving voltage to speaker, 300mV; measurement bandwidth, 2kHz).

The blue trace in fig.2 shows the output of the LSX's woofer measured in the nearfield. The minimum-motion notch in its output lies at 58Hz, revealing that this is the tuning frequency of the flared port on the rear panel—a relatively high frequency, but to be expected in a small speaker such as this. The port's output (red trace) peaks between 40 and 80Hz, but a sharply defined resonant mode is visible at 800Hz. Again, I couldn't hear this mode at the listening position, presumably because the port is on the speaker's rear panel. Both the port's and woofer's low-frequency outputs roll off faster than the 12dB/octave slope that is usual in a reflex design. I suspect that this is to protect the tiny woofer from subsonic overload, but it means that the complex sum of the nearfield woofer and port responses (fig.2, black trace below 300Hz) rolls off with a sixth-order, 36dB/octave slope below the port tuning frequency.


Fig.2 KEF LSX, anechoic response on tweeter axis at 50", averaged across 30° horizontal window and corrected for microphone response, with the nearfield woofer and port responses and their complex sum, respectively plotted below 300Hz, 1kHz, and 300Hz.

The black trace above 300Hz in fig.2 shows the LSX's farfield response, averaged across a 30° horizontal window centered on the tweeter axis. It is astonishingly flat, though some suckouts can be seen in the top two octaves, these interference effects resulting from the coaxial tweeter being mounted at the center of the woofer cone. One surprise in this graph is that the speaker's output drops like a stone above 23kHz, suggesting that the LSX digitizes its analog input to a 48kHz sample rate, perhaps because the Phase Correction was enabled. This might also contribute to the latency I noted earlier. Repeating the measurement with optical digital data (not shown) indicated that the LSX's metal-dome tweeter has a significant oil-can resonance at 37.6kHz, well above the audioband.

The plot of the LSX's horizontal dispersion (fig.3) indicates a well-controlled radiation pattern. The evenly spaced contour lines suggest that a pair of these speakers will offer stable stereo imaging. Fig.3 shows that the on-axis suckout at 8.9kHz tends to fill in to the speaker's sides, but also that the speaker becomes very directional in the top octave, a region where the on-axis response also lacks energy. I suspect that the LSX is balanced to be listened to in the nearfield—on a desk, say—rather than at a distance. I haven't shown the LSX's vertical dispersion, as it was basically identical to the behavior in the horizontal plane.


Fig.3 KEF LSX, lateral response family at 50", normalized to response on tweeter axis, from back to front: differences in response 90–5° off axis, reference response, differences in response 5–90° off axis.

Turning to the time domain, the LSX's use of digital correction can be seen in its step response (fig.4). The outputs of the tweeters and woofer arrive at the microphone at the same time, resulting in an almost perfect positive-polarity, time-coincident, right-triangle shape. Other than a ridge of delayed energy at the frequency of the on-axis suckout, the KEF's cumulative spectral-decay plot (fig.5) was superbly clean.


Fig.4 KEF LSX, step response on tweeter axis at 50" (5ms time window, 30kHz bandwidth).


Fig.5 KEF LSX, cumulative spectral-decay plot on tweeter axis at 50" (0.15ms risetime).

I was impressed by the KEF LSX's measured performance, and will explore its sound quality further in a Follow-Up.—John Atkinson

KEF, GP Acoustics (UK) Ltd.
US distributor: GP Acoustics (US) Inc.
10 Timber Lane
Marlboro, NJ 07746
(732) 683-2356

Bogolu Haranath's picture

LSX is a good example of a glimpse into the future ....... More of these types of DSP enabled active speakers are coming our way :-) .........

Indydan's picture

More are coming, but passive speakers will always dominate.

vincentvm's picture

Highly doubtful, but I see the wishful thinking of the old guard.
Let them have their Harbeths and BBC LS\3 and spendors.
Then we will have Devialet and others map them and goose them to unheard performances. How passive are speakers then, when they are being Borged into the future.

Indydan's picture


MhtLion's picture

Can an external DAC be used? I see an AUX port but no RCA or Balanced input. Its internal DAC must be at best $30 a pop or less (more likely less) and is a limiting factor. Also, the sound cannot be upgraded at any means in the future.

But, I also see the fact each driver is coupled with its own internal DAC can be an advantage. Also, if an analog signal is received, then it would need to go through another DSP in order to actively drive each driver.

I hope some industry standard will be established that DAC manufactures can produce a standalone DAC which works with active speakers. It will be amazing to see a Yggy with three outputs per channel with a custom crossover setting for each speaker, which can be downloaded online.

kipoca's picture

These are DSP speakers, so using a digital source with an analog converter would convert it back to digital and then back to analog. I don't know about this particular speaker, but a DSP speaker can use a DAC for each driver in the amplifier stage.

Kal Rubinson's picture

There are many DSP-based active loudspeakers on the market already, wireless or not. Most are either life-style gadgets (not our concern) or professional products and neither have been featured in Stereophile. Two exceptions are the Beolab 90 and the Kii Three and it is clear that the highly integrated nature of these designs preclude what you are asking for. It would greatly and, unnecessarily, increase complexity and compromise the inherent value of the integration.

Bogolu Haranath's picture

KR could consider reviewing the new Eikon speaker system, which was shown at AXPONA 2019 ...... It has DSP and room correction ...... Stereophile reported about the Eikon system :-) ..........

SteveG's picture

I think I’ve seen mention of using these wired via Ethernet, along with the suggestion that they sound better this way.

kipoca's picture

Wired has a higher bitrate.

SteveG's picture

I think I’ve seen mention of using these wired via Ethernet, along with the suggestion that they sound better this way.

beave's picture

"I suspect that this is to protect the tiny woofer from subsonic overload..."

Isn't the proper word here infrasonic, not subsonic?

Ali's picture

I still prefer 2 Apple Home pod far more. Thats it.

wozwoz's picture

Leaving aside the fact that a rational informed person would not want to needlessly and pointlessly radiate their own home with wi-fi, the biggest failing of the review is not to expound on the line: "signals can enter the LSX wirelessly via Bluetooth 4.2" etc ... which is a lossy massively compressed medium and that has no place in a magazine calling itself "Stereophile". Bluetooth is for noobs who do not know better .. with substantially worse quality than redbook CD ... and since the suggested inputs are streaming (Spotify) ... it only gets worse. Buy yourself a $20 cable, stick in under the carpet if you don't want to see it, and get serious.

Robin Landseadel's picture

"Rational informed people" is one of them straw men. First, seen any rational informed people lately? Second, like it or not we are awash in wi-fi anyway. And if I want to hear Blandine Verlet's recordings of François Couperin I'm going to be streaming it because the physical issues are unobtanium. The reality is that streaming is the new norm. "Substantially worse quality than redbook CD" is meaningful only when the playback gear can actually deliver 44.1/16. It usually doesn't, particularly with older gear. And streams can do better than that anyway. In any case, my smartphone lashed to good headphones gives me better sound than most of what I've owned over the last 50 years.

ok's picture

do most of my listening through phone-plugged ear-cans nowadays, both chosen on grounds of available measurements and good looks. When I first realized the quality, quantity and convenience that can be had for no more than 1k (fully functional smartphone bonus included) I felt like an old fool no less. Yes, I still enjoy my once-indispensable home system under certain conditions; but the hard-earned money I certainly regret, though I know it was the only way those days back then.

Robin Landseadel's picture

It's not as if I spent the kind of money we see regularly for new gear in Stereophile. My stuff ain't junk, but it ain't new either. And radio still sounds like radio. Digital streams sometimes reveal low-bitrate sources, but sometimes the sound is as good as any CD I've heard, it all depends. When I play a stream over one of my old-fashioned "stereos" it usually sounds a little better that what I used to get from LPs and CDs. The reality was that during the "Golden Age" of analog some releases were great, most were only ok, some awful. Same as it ever was. Chances of first rate sound are greater now than then. If it's a choice between wi-fi throughout the house or fuzz on the stylus, I'll take the wi-fi.

Jim Austin's picture

I would never use Bluetooth for serious listening, but I've come to appreciate it as a feature. Why? I enjoy movies, but I'm not serious about video. This means I usually watch on my laptop computer, with the computer sitting in my lap. But I do like some good sound, so I like to cast the audio to my main audio system. Bluetooth makes it easy, and AptX (supported by KEF LSX) means minimal latency so good voice sync.

High-end audio companies are increasingly supporting Bluetooth in their integrated devices. One example is the new Mark Levinson No. 5805 integrated amplifier, which I have in-house right now. It's capable of very good sound--but its also very easy for me to sync my laptop and watch a movie.

The new-ish aptX HD is supposedly has quite good sound, although I haven't investigated it sufficiently to know whether their "high-res" claims have merit.

Jim Austin, Editor

Bogolu Haranath's picture

Watching movies on a lap-top computer, when 8k displays and projectors with HDR are showing up on the market? :-) ........

Jim Austin's picture
spectral75's picture

Both Bluetooth and Airplay support lossless Red Book transmission, both of which the LSXs support. Looks like you are the "noob".

CelticMan's picture

What a complete and utter snob you are. You don’t have to like wireless technologies but it’s also obvious you have no clue about them. A pretentious expert.

Bogolu Haranath's picture

"Love Me Tender" ......... Elvis Presley :-) .........

tonykaz's picture

Stereophile is the ONLY place that a Picture of the Lower Printed Manufacturing details are showing, I just did a Google search trying to reveal a better photo of the Made in UK Lower Label, none exist. There is none offered by ANY of the very large number of Reviews and/or reviewer' comments! Even Stereophile avoided mentioning the Obvious fact that this is a complex Chinese Product sellling for Made in UK Pricing " as stated by one review writing buyer/owner" .

This LSX is not an Audiophile Loudspeaker, is it? It's a Colorful Consumer Product destined for the Shelves of Walmart, Best Best Buy and Amazon.

So, I have to think that this is a Paid for Review. I'm profoundly disappointed by this realization.

Is TAS reviewing this little Plastic device? Is Darko ? Is 6-Moons ?

So, can/should I ask that our Editors present some sort of Statement that they are going to be sellling reviews & endorsing Non-Audiophile Products to help defray the increasing costs of keeping themselves financially sound. ( pardon the un-intentional pun )

Dammit, I knew Raymond Cooke. Can I feel saddened that his creation and considerable UK exporting prowess is now a Chinese Company making plastic appliances ??? ( and hiding their Country of Origin )

Tony in Michigan

ps. by the way, one Amazon Buyer/owner complained that there is NO support for this device, did anyone at Stereophile attempt to get any sort of assistance from KEF? is there ample support for this product ?

Bogolu Haranath's picture

TAS, Darko and AudioStream have reviewed LSX, as far as I know ........ TAS and Twittering Machines have reviewed similar, but more expensive ($2,500) LS-50 Nocturnes, as far as I know :-) ..........

Both LSX and LS-50 Nocturnes have received very favorable reviews by all the reviewers :-) .........

tonykaz's picture

You are submitting further evidence of my Neurosis:

This 2+2=4 and I mad as hell about it, maybe even hate it!

Tony in Michigan feeling miserable.

John Atkinson's picture
tonykaz wrote:
I have to think that this is a Paid for Review. I'm profoundly disappointed by this realization . . . So, can/should I ask that our Editors present some sort of Statement that they are going to be sellling reviews & endorsing Non-Audiophile Products to help defray the increasing costs of keeping themselves financially sound.

This not a pay-for-play review. Stereophile does not publish reviews that are paid for by manufacturers. Frankly, Tony, I am saddened that you make this accusation.

I have written a followup on this little gem of a speaker for the June issue, where I discuss its sound with a wired connection and hi-rez files.

tonykaz wrote:
Dammit, I knew Raymond Cooke. Can I feel saddened that his creation and considerable UK exporting prowess is now a Chinese Company making plastic appliances . . .

Hong Kong-based Gold Peak bought KEF (and Celestion) in 1992, so you are a little behind the times with this revelation.

John Atkinson
Technical Editor, Stereophile

tonykaz's picture

Thank you for being saddened and thank you for addressing my "accusation" ! I have confidence in You and Stereophile and very much hope to maintain that confidence. I needed you to step forward and declare me wrong. ( especially if I am and when I am )

Yes, I am well behind the times. It was Tyll and Steve G. at RMAF 2011 that re-kindeled my long absence from Audio Hobby interests.

I didn't intend to be rude or accusational in a painful way, I was writing from a tearful & painful realization that the World I knew is transitioning into a World I'm uncomfortable with.

For me, Raymond Cooke was an Industry Leader, KEF was an Aston Martin type Product Engineered and Built in Maidstone. KEF today is something much ( considerably ) less and I'm being neurotically unhappy about it. ( as I am about any Company that Off-Shores to save on Labor ).

I now understand that KEF was purchased outright.

Tony in Michigan

ps. I read the Specifications to say KEF England with no mention of China. I saw the photo of the Bottom 1/4 20 Mounting that HR mentions and notice all that print being fuzzily out of focus an unreadable. I then did a proper Google search only to discover that China is never mentioned or hinted on by Anyone writing about this device.
I concluded that it's an "INTENTIONAL" non-disclosure of important decision altering information.

ps. my batting average is below .500, I'm often wrong

John Atkinson's picture
tonykaz wrote:
I read the Specifications to say KEF England with no mention of China. I saw the photo of the Bottom 1/4 20 Mounting that HR mentions and notice all that print being fuzzily out of focus an unreadable.

It does clearly say "Made in China" on the original photo of the LSX's bottom panel but at the 600-pixel image width that is standard on our website, it is illegible.

John Atkinson
Technical Editor, Stereophile

tonykaz's picture

Thank you for confirming my visual analysis. I went on a Google Image hunt for a Clear view of that lower mounting panel to realize that "only" Stereophile decided to show it's quarter-twenty threaded brass mounting panel but not a legible rendering. ( all other photos are sharp ) feeling the inconsistency being a decision to not let us have a good read of it's contents. ( by the way, when you had someone in your own listening room, I was enlarging the images to reveal the origins of the cabling hanging on your rear area. I own a high resolution monitor for technical analysis purposes, I'm not a voyeur )

I applaud Mr. HR for mentioning the trip-pod mounting capability of this transducer system, he is the only person doing so. Not even the Owners Manual describes this PRO type feature. But still, no surprise, HR is the best Audio Reviewer out there today, he's rapidly catching up with the All Time Best : Alex Dykes and he's surpassing the great Tyll. ( I think )

Tony in Michigan

ps. my big toe is getting sore from kicking KEF, I'm standing down!

Bogolu Haranath's picture

May I nominate LSX for budget component of the year, editor's choice award of the year and overall product of the year 2019 of Stereophile? :-) .........

Indydan's picture

Do you work for KEF? You promote the LS50 wireless and the LSX every chance you get.

Bogolu Haranath's picture

No, I don't work for KEF ...... I don't have any affiliation with any audio company ....... I just comment about any audio product which is favorably (or, otherwise) reviewed in Stereophile and other publications/websites ...... I just love to hear great music and great music reproduction :-) ........

Ortofan's picture

... following link:
The ninth line below the KEF logo clearly reads "MADE IN CHINA".

If you want a new set of KEF speakers made in the UK, you need to choose from the Reference series or the Blades.

tonykaz's picture

You are a good researcher.

I looked for a half hour and quit.

This is a nearly impossible detail to find, it should be OUT-Front because it itself is a "Decision Altering" Purchase Factor for a considerable percentage USA folks increasingly pissed at Corporate Off-Shoring. Especially with it's Premium Price and that KEF are Marketing it to be a UK product. ( with tricky phrasing to encourage folks to think it's a UK product )

The next "still-unanswered" question is Service. Can this thing be serviced and is it Supported? For $1,100 should we expect it to have support and service ? or Is this device something we return for an Exchange with the broken one re-sold as repaired B stock from an eBay warehouse fulfiller in Central USA. SONY has abandoned Service of any SONY product I'm aware of, especially their Cameras. Canon services their Cameras!

My persisting feeling is that Audiophile Products are Artisan built, by Skilled Craftsman, designed to deliver consistant Performance that will assure retained value for Generations.

Why waste funds on trendy nonsense devices that will be on next year's Garage Sale Tables?

I read Stereophile for Lasting-Quality, decision help & understanding. ( and Steve G )

I go to David Pogue for Pop-Culture Technology Device-Advice.

Tony in Michigan

ps. do these Green KEFs belong to Michael Jones ?

hb72's picture

if you were able to read the (excellent!) measurements you'd recognize these speakers are by no means just a "colourful consumer products".

Of course, measurements do not draw the complete picture but provide some very helpful information about basic balance, quality, and, e.g., time-alignment, in which resepct the LSX is quite perfect and thus better than ca 99% of speakers on the market.

Bogolu Haranath's picture

Agreed ........ LSX is one very good example of what an active, DSP enabled loudspeaker engineering can do :-) .........

Not just another 'pretty face' ......... The beauty is more than 'skin deep' :-) ............

tonykaz's picture

Yes, you are correct, I didn't read the measurements. I almost never read the measurements even though I'm an Electrical Engineer. Good call !!!

Your summary of these Transducer Systems agree with the majority of the Reviewer's Statements but not necessarily with the majority of the actual buyers writing published reviews.

Reviewers are close to 100% positive on these things, the Reviewers publishers seem to add an additional 10% approval making these devices the finest Loudspeaker Transducer System in the Known World -- This Month? ( am I being cynical ?, hell yes! )

Actual Owners with real life experience report significantly lower approvals with levels of disapproval for various details. ( typical of any product, nothing special about this product's acceptance patterns )

So, the actual customer, man-on-the-street, yawns at these cute little things about 50%, while Reviewers seem to be 110% positive.

One year from now, we'll know better. Will our Audiophile Journalists include these little transducers in their stated "Owned" associated gear? I'm guessing no.

Even so, ( after all my bitching and moaning ) I might own a pair when an Amazon Seller puts them on closeout for $229.00 Free Shipping. Even then, I might return them if they don't perform as expected. Such is Life for a product designed to be a Race to the Bottom / Impulse buyer product ( a phrase I might be asked to retract ). These are not LS3/5a Heirloom type products.

Above is "MY" opinion. I'm not trying to throw ashtrays here.
I'm a KEF fan of 4 Decades.

Tony in transit

ps. Thank you for Writing, I need calling out and you make dam good points!!!

hb72's picture

given the world we are living in (and how it changes in recent years), I do (and one really should!) appreaciate a healthy deal of scepticism, even though it might appear a bit exaggerated. :)

Bogolu Haranath's picture

Amazon has 62% five star ratings out of 29 reviews, so far ......... for whatever it is worth :-) .........

tonykaz's picture

Why aren't those ratings 100% ?

The Brits buyer/owners have plenty of "experience" informed commentary, they are being sold this device to be a traditional UK KEF device and only learn of it's true origin after careful examination of the devices themselves.

I am directing this comment to you, specifically. I am not attempting to generate a landslide of public anger.

However we are having a useful public discussion.

And : I'm not mentioning a Company Name or Product Name.

I consider this a Philosophical discussion about Corporate decisions on Global Marketing.

Tony in transit

Bogolu Haranath's picture

I agree with your point of view ....... I just mentioned Amazon reviews as an additional, supplemental information for those who may be interested in such information :-) .........

tonykaz's picture

Yes, of course.

I just don't think that anyone reading this Publication ( stereophile ) will find the colorful little appliance as an Audiophile Product ( especially considering it's "Perfect" measurements. It's just a trendy adaptation of Wireless technology.
Audiophiles know fully well that outstanding sounding Componentry will typically measure rather poorly, especially Loudspeakers. ( I'm gonna catch hell from measurers on this )

Having said all the above, with conviction, I'm prepared to be completely wrong. I'll then issue apologies and retractions in BOLD letters.

In a way, I hope that I'm wrong because I'd like to think of us going forth into a better World.

On the Bright Side of China :

China has only been in ONE War since 1500 AD., with Viet Nam, they got clobbered, just like we did. It was a short War.

China publicly executes Drug Dealers! They drive the dealer around to show everyone and then....

China doesn't tolerate the Sale of War Guns to civilians!

China's Governance is far more Humane than Western/Christian based Governments.

China is an Advanced Civilization and has been for thousands of years. They don't Genocide.

China has never exported War, Colonialism, Imperialism, Buddhism, etc...

I greatly admire China. The Chinese leadership are the fathers and protectors of families.

There is no smell of racism in China. ( as far as I've come to understand )

I could go on and on....

Tony in transit

ps. one of my Sons married Asian

Bogolu Haranath's picture

Agreed ........ I don't think LSX is gonna replace any audiophile main system ........ It could be considered for a 2nd or a 3rd system ........ The cost and the ease of use are attractive as HR mentioned .......... At the moment there is no American made product quite like the LSX .......... That situation may change 2 to 5 years from now :-) ..........

CelticMan's picture

You talk too much. You need something to occupy you more!

dalethorn's picture

For whatever it's worth, many products that I've found to be good quality and reliable get a lot of one and two-star reviews on Amazon. Not the majority of the reviews, but enough to wonder if 1) They got the genuine product and 2) What they did to it after they installed and used it.

Indydan's picture

Garbage on Amazon. You get what you pay for.

dalethorn's picture

Garbage says...

Bogolu Haranath's picture

Talking about 'pay-to-play' ....... I could not find any such thing as 'John Atkinson Foundation' ....... I have searched for it on the internet :-) .........

.... also, there is no 'Atkinson Tower' or 'Atkinson International Hotel' in Beijing :-) .........

tonykaz's picture

Are you kidding, I was running his Foundation and spent all the money on Taco Bell Salads.

Have another look for : "Save the Audiophile Foundation" , donate all the money you can spare, I'm gonna need it to continue my product bashing. ;-( ....

Tony in Michigan

musicophile's picture


May I ask what was the piece where you could point out each singer in a large chorus? And what was the source? Spotify over bluetooth or something else?


Charles E Flynn's picture

Mostly made in China:

jimtavegia's picture

What I have done is taken a Yamaha MG-10XU ($199) that has 4 mic pre amps and 3 line level stereo inputs driven by my Mac mini USB. Using the USB takes up the 4th stereo line level in. The Yamaha handles 24192 flawlessly and with a decent microphone gives me the best possible FaceTime anyone could want.

The Yamaha also has built-in effects from hall and plate reverbs to make your voice sound as good as you want, and even has 48Vdc phantom power for condenser mics as I run a Sennheiser e865 though mine and folks tell me it sounds great. It does even with a $99 Rode M1 as well. The great Shure SM 58 is also an excellent $99 choice. Music through it sounds superb even on headphones.

Now you can use the Yamaha to drive any powered loudspeaker you want and I use some JBL 305s that sound just fine for me and my wife has some Behringer's off her computer as she is much less into audio as I, but the Behringer's sound fine. All for under $500, less microphone, and you may not need one if you don't do FaceTime.

Many ways to make computer audio sound great and I am sure the KEF options is a good one.

jeffhenning's picture

For my bedroom, I bought a pair of LSX's and some discounted Boston Acoustics ASX250 subs. I added some KEF 2ft. stands, Mogami cables, Sorbothane hemispheres, 20lbs. of steel shot & another 20 of sand for the stands as well as Auralex Baby GRAMMA platforms and SVS sub feet.

I have a much more expensive system in the basement that's centered around KEF LS50's and Rythmik servo subs, but the set up is very similar as is the way they radiate into the room.

I have 3 take-away's to offer:

• The LSX's are a pretty fantastic product and offer the promise of a great sound system if they would just add a couple bands of parametric EQ into the mix with their setup app so you can take it to the next level and do some real room/playback adjustment. That said, the controls available through the app are very impressive.

• The LSX cabinets are not built to nearly the same level as the LS50's (no surprise given the price point) and they do "sing" (vibrate) a great deal when you turn the volume up even with a 120Hz hi-pass filter working. These are not speakers meant to produce more than 98-100dB even with the hi-pass filter maxed.

• You can never have a truly great sounding system without a great sounding room... already knew that, but, given the commonality of the systems, that has been put into stark relief. My wood floored/drywalled bedroom has nothing, but a bed to absorb sound. The bass is uneven, the mids are a touch overpowering and the stereo image is vague. My main system is in the basement and I'm setting it up as a LEDE room (live end/dead end). It's sounds incredible. I'll forgo the description, but anyone would be and is impressed when they hear it.

One final thought: when you place a tubular speaker stand on top of a sub, even with SVS sub feet, you still need to fill them with steel shot and sand. The difference is not subtle and it's effective & cheap!


Carloscastaneda's picture

tony in Michigan is spewing racist bs. It dismays me that stereophile would feed the hatred in the world like this. I hear a lot of casual racism towards Chinese people here too but it should not be normalized. As Billy Bragg used to say, even the communists fall in love and have babies and families. Dehumanizing comments like Tony's have no place in society.. Peace. Plus I'm probably going to buy these speakers because of this review.

tonykaz's picture

Discussing Global Manufacturing Economics is not reducible to Racism.

My Position on Manufacturing evolves from thouroughly documented Data Bases.

Dismissing my Voiced Complaints as Racist is itself a Racist Comment.

My position is to point out that our Captains of Industry are Outsourcing Labor to disadvantaged Slave Labor. Buying Walmart products is endorsing and supporting the Chines Slave Labor Policies of "OUR" Vastly Wealthy Corporate Class.

I'm against Slavery !

I'm against Walmart/China Slave Masters hollowing-out our Downtowns and turning our Skilled Workforce into minimum wage workers at Fast Food Outlets.


I applaud Europe & UK for Yellow Vesting to protect themselves.

I applaud our HighEnd Audio Companies that are striving to Build Quality Products that will probably outlive us and maintain or increase in value to our inheriting generations. ( thank you Steve G. for todays important Idea/Concept Philosophical Contribution )

Tony in Michigan

ps. put me down as fully supporting all Races ( even Rep.Omar from Mn )

ps. my personal family & Extended Family is/are multi-racial, I love all of us.

Jason Victor Serinus's picture

You wrote: ps. put me down as fully supporting all Races ( even Rep.Omar from Mn )

Rep. Omar is not a race; she is a human being who speaks her mind as freely and, if I may be permitted to say so, as carelessly as you do.

tonykaz's picture

Thanks for writing.

Of course she's not a Race. I admire her and all she represents.

On speaking minds.

I am an Analytical Electrical Engineer retired from Large Scale Manufacturing where speaking of minds is the only communication appropriate, acceptable and Demanded!!! Industrial communication has a standard lexicon of socially distasteful terms & phrases that are only just now going mainstream over internet based Media and are Powerful Descriptives for illustrating levels of Priorities, levels of urgency and other High Noise Enviornment Circumstances. I'm a Factory Rat for over 5 Decade where only Clear, Direct, Sharply pointed & accurate communication of information is appropriate. It's not insulting ( or Racist ) if it's accurate!

My Wife is a Minister Care Giver/Social Type who speaks with great care to not hurt anyone's feelings.

I accept your spoken disapproval of the things I say, the points of view I have, the positions I take. I will continue to admire you, cherish your work, value your contributions. In my World, where two people agree, only one is thinking, if you don't stand up for your point of view than I'm not quite as enamored with you as I should be.

I remember clearly you snapping back when I was commenting on the photo of you in front of those towering Mormon Loudspeakers. ( I won't restate my rather ugly comment about re-education )
I admired you Shooting back with both guns blazing in defense of yourself. I was rather proud of you for your written/spoken position in Life and all of your recited History.

You're a good person : The highest Award I have!

Tony in Michigan

ps. are you gonna do that Schiit Class A Amp?

ps. I'll expose myself to you. I'm a Neurotic, Psychotic and Depressive ( not suicidal ) and I typically have a lower estimate of myself that most people have of me. I'm probably a 3 of 10 as a human being, even my own mother knew this by the time I was 10 years old. When or if you say that I'm bad, I'll agree with you more that you can imagine. My wife & children & grandchildren say that I'm a good person, I tend to not believe them. Even so, I like myself!

Jason Victor Serinus's picture

I truly appreciate your response. As for the Schiit, others are better equipped to evaluate it fairly. It's not an appropriate piece for my reference system, and won't work with the self-powered speakers in our living room and my office.


tonykaz's picture


Thanks again for writing.

Tony in Michigan

Bogolu Haranath's picture

In that case, may be JVS could review the new B & W Formation Duo wireless, active speakers? ........ somewhat similar to KEF LSX :-) ..........

dalethorn's picture

"My position is to point out that our Captains of Industry are Outsourcing Labor to disadvantaged Slave Labor. Buying Walmart products is endorsing and supporting the Chines Slave Labor Policies of "OUR" Vastly Wealthy Corporate Class."

Ordinary people will almost invariably buy the cheaper product, especially if they can return or exchange it when defective or whatever, at the local Walmart etc. So as we cast around for someone to blame, it's not so much the fault of the little people or the big shots, it's the system. Large-scale manufacturing and distribution, international shipping and trade agreements, and the risks that accompany these things develop over a long period of time. So you have choices, and not merely where you spend your dwindling paycheck. You can participate to change the system at many points, such as writing reviews, joining a trade group or APICS, etc. etc. There aren't any shortcuts.

Thomas Collins's picture

China is notorious for lower quality control and difficulty in obtaining product support. Did I miss something?

ivayvr's picture

I believe that even a cursory interest in the product that is being reviewed would reveal that you don't need an iPhone or iPad to control it. It can be controlled either by an Android device or by an Apple device. The original statement is unfair to the manufacturer because it may limit the number of people interested in the speaker because they may have additional expense for an Apple device.
If the above omission is a result of old age or LSD, as mentioned in the review, some additional proof reading/editing may be beneficial.

Jim Austin's picture
I regret that we overlooked this during editing. I've added a note to the online version. Jim Austin, Editor Stereophile
musicophile's picture

Hello. I'm still waiting for the answer to my question what was the piece with the big chorus where single voices could be pointed out. Thanks.

Timbo in Oz's picture

4th order/ 24db / octave, surely!

But it IS possible that there's an ELF filter in the active circuits.

Thomas Collins's picture

So only an Apple product can be used to control these? I surely hope that's a mistake on Stereophile's part.

Herb Reichert's picture

but try "Christmas at Kings College" on Tidal - it should give you some heads to count

Bogolu Haranath's picture

Would HR be interested in reviewing the new B&W Formation Duo wireless, active speakers, also (4,000/pair)? ...... They are supposed to be totally wireless, except for power cord connections :-) ........

Linnie01's picture


I am seriously considering purchasing the LSX.

My only concern (maybe unfounded) is long term (10+year) reliability regarding the electronics, not the drivers.


I really want to avoid the disposable toaster syndrome at $1,099.

I am also strongly considering the Triangle LN01A’s @ $799 (2 year warranty) but a cable between speakers is needed.

I would really appreciate your thoughts sooner than later.

Many thanks!

Linnie01's picture

One last comment ....with no real history of WiFi speakers, no one reason has the answer to my question. However, I am looking for gut feelings at this point.

With so much tech stuffed in these boxes, I worry about the long term at this price point. Thanks!!

ednazarko's picture

...but I had two different pairs of powered studio monitors. Both were M-Audio branded. One large size and one small. Purchased in 2001. A neighbor just bought both sets for their basement A/V system, a pre/pro, no amp, using the large set as the fronts, the small set for the rears, and they found a powered center of some other brand.

Those speakers played everything from the MC5 to Gregorian chant for around 18 years.So based on that experience, I reckon the electronic bits of the LSX will be as durable as any other DAC or class-D amplifier.

Jim Austin's picture

Durability aside--even potential noise issues aside--there are downsides to sticking a lot of stuff inside one box. I think about this often in terms of streaming DACs: Very compact, but a DAC is more or less a stable technology: If it sounds good now, it's likely to sound good in 10 years.

Streaming, though--all those sources delivered over the Internet--are likely to develop and change. Best to keep that all in a separate box, IMO, then connect that box to the DAC via the best-sounding connection. (I'm not 100% sure that is--not sure it's always the same.)

Wireless is convenient--just decide how important it is for you to eliminate the cables. The LSX may last forever the odds are on a simple speaker, with a box, drivers, and robust crossover parts, for durability.

Jim Austin, Editor

douglas1969's picture

Hello how did you connect these to your computer using USB if there is no USB input in the back of the speaker? Did you use a USB dac with toslink output maybe?

RobertJS's picture

He was referring to the LS-50 Wireless being able to connect to USB/RCA not the LSX.

In my short time with the LSX on my desktop, I have found the best sound to be with a Ethernet network connection and the RJ45 to the Slave while being streamed to with my Roon Nucleus+. I am able to tailor the sound further with the Parametric EQ in the Roon. Another nice benefit is the the Roon will wake the LSX from standby when you press play.