Ayre Acoustics KX-5 Twenty line preamplifier Page 2

Even when I began playing music, the KX-5 Twenty's user interface hindered rather than helped: With a CD playing in my Sony disc player, and with the appropriate input selected and the preamp's volume turned up to "20" (of a range of "0" to "46"), the signal still wasn't making its way through my amplifier and speakers. I'd assumed the Ayre wasn't muted because, according to the manual, when Mute is activated, whether via the remote or the front panel, this "temporarily [turns] the volume of the KX-5 to 'zero'"—and the front-panel display still read "20." It turns out that when Mute is activated, "0" or even "zero" does not appear on the display—rather, Mute is visually indicated by the display illuminating all of its decimal points. If there's a less intuitive way of getting across the notion of mute, I can't imagine it.

The user interface and owner's manual both need work.

Happily, the Ayre KX-5 Twenty sounded good. Really damn good.

As my listening notes remind me, singer Lee Feldman's voice in "Give Me My Money," and in other songs from his indispensable I've Forgotten Everything (CD, Urban Myth UM-114-2), sounded "amazing: lifelike and present and lacking in timbral colorations or other distortions." In "Me and My Sara Remaining," the way the accordion insinuates itself into the song was real and right, and in "Hippy Store," the sense of the backing combo—electric guitar, electric bass, Hammond organ, drums—playing between my speakers was uncanny. As I came to realize during its time in my system, the KX-5 Twenty was virtually unparalleled in its ability to suggest scale and spatial perspectives. With this disc, the only respect in which the Ayre could be bettered was its slight lack of texture in the sounds of the electric bass (although notes in the acoustic piano's left hand sounded "stringy" enough).

That lack of texture followed the Ayre to Leonard Cohen's second album, Songs from a Room (CD, Columbia/Legacy 88697 04740 2), on which the sound of the double bass was a little too smooth and rounded over. At this point in my listening I paused and double-checked these observations by reinstalling, for a couple of hours, my Shindo Laboratory Monbrison preamplifier—the differences between the two products' portrayals of sonic textures were quite apparent. But notes from that double bass were clear of pitch, and nimble. Voice articulation was superb without being clinical—especially in "The Partisan," I found it easier than ever to understand the three verses sung in French. More important, every song on this album was as moving as I always hope and expect them to be.


Sonic touch and force came across well through the KX-5 Twenty, albeit not quite as well as through the very best preamps I've heard. The soft, pizzicato cellos and double basses that begin Bruckner's Symphony 5, in a recording by Jascha Horenstein and the BBC Symphony Orchestra (CD, Intaglio INCD 7541), had decent pluck. At the other end of the scale, louder passages came across with clarity and poise: Never once did the music sound harsh or pinched or smaller than it should. In a larger and altogether more important musical sense, the Ayre allowed the Bruckner its strength of line and sense of purpose: heard through this preamp, every minute was electric.

The KX-5 Twenty also did well with rowdier music. In "Tanya," from Dexter Gordon's One Flight Up (LP, Blue Note/Cisco Music BLP 84176), the tension in Niels-Henning Ørsted Pedersen's double-bass lines—especially his double-stops later in the track—came across very well, and the sound of Art Taylor giving his drums hell was a delight. On this recording as others, more texture—in the sounds of all the instruments, really—can be had through better and generally more expensive electronics, but I found the Ayre satisfying, Gordon's tenor sax sounding especially good. And from a recently acquired mono copy of the Yardbirds' Five Live Yardbirds (LP, UK Columbia 33SX 1677), the sound of the 19-year-old Eric Clapton's electric guitar fairly leapt from the speakers. Hearing that record through the Ayre had me thinking not about spatial this or color that, but about what a great, raw-sounding band that was!

Indeed, I suppose the truest test of any piece of audio gear is its ability to connect the listener with the music, as when the product allows its user to appreciate new or heretofore underappreciated music. So it was when I played Grieg's incidental music from Peer Gynt, performed by Øiven Fjeldstad and the London Symphony Orchestra (CD, London/Classic Compact Discs CSCD 6049). I've always considered Grieg a second-rate composer (and not even a first-rate second-rate composer, as Richard Strauss once described himself), and I've tended to regard the Peer Gynt music in particular as nationalistic fluff, but minus the spark of genius that informed, say, Elgar's nationalistic fluff. I reached for this CD only because I knew it to be a recording of very high quality: the cardinal audiophile sin. But through the Ayre, that music steadfastly refused to be taken as mere audio-review fodder, and I found myself drawn into Grieg's melodies and orchestrations as never before. And I couldn't help hearing how the third selection, The Death of Ase, might have influenced Franz Waxman's brilliant score for The Bride of Frankenstein. So in the best of ways, the KX-5 Twenty earned its keep.

A final note: On the Ayre's last day here I unplugged it, removed its top cover, and had a look inside—after which I replaced the cover and remade all the connections, hoping to listen to just a few songs more. But when I flipped its rear-panel power switch, a single red light and the letters AC, in blue, appeared on the display. I consulted the manual and learned that this was the preamp's way of telling me that my household AC wasn't serving up the correct voltage. I shut down the preamp, measured my household current—a perfect 120V—and started over. This time there was no warning message, and everything worked just fine. I doubt that this episode reflects a problem of any sort—perhaps the line voltage had dipped overnight? I mention it here only in the interest of t-crossing and i-dotting.

I enjoyed the time I spent listening to the KX-5 Twenty—the time spent interacting with it, less so—and although I prefer the sound of my all-tube Shindo Monbrison preamp, the Ayre's remarkable and utterly nonclinical clarity, and its convincing, commandingly good spatial performance, made big impressions on me. Sonically, musically, and as a product of 21st-century American audio craftsmanship—that VGT system really must be seen to be appreciated (footnote 1)—the KX-5 Twenty offers decent value, especially to hobbyists who already own an Ayre amplifier; those who are starting from scratch and who enjoy Ayre's house sound might consider spending another $5000 and buying, instead, their AX-5 Twenty integrated amplifier. Recommended.

Footnote 1: The legal department of TEN Publishing, parent company of Stereophile, may rest assured: I in no way recommend that owners of KX-5 Twentys go poking around inside their preamps, especially without first unplugging them and draining their power-supply capacitors.
Ayre Acoustics, Inc.
2300-B Central Avenue
Boulder, CO 80301
(303) 442-7300

mrkaic's picture

...what this means: "Instead of adjusting volume in the traditional manner—with a potentiometer that discards varying amounts of the product's signal gain—each phase of each stereo channel of the VGT contains 46 discrete resistors that, selected with a rotary switch, create 46 distinct variations on the preamp's voltage-gain stage, for a range of 46 volume levels. Thus there are fewer parts than usual in the signal path, and the preamplifier as a whole, from signal inputs through output buffer, is always maintaining an optimal S/N ratio."

I am especially intrigued by the optimal(sic) S/N ratio. How does one determine this optimality?

Axiom05's picture

The volume is controlled by changing the gain of the preamp. Changing the volume changes the resistor value in the signal path. This is not a passive preamp, every volume step has a specific amount of gain. Despite being conditioned to think that a passive preamp should sound best, this preamp sounds absolutely amazing: extremely quiet and smooth. The drawback to this approach is that you need a lot of resistors to effect the volume changes, the smaller the steps, the more resistors, the higher the parts cost. This is why the KX-5 Twenty has about 1.5 dB volume change for each "click" of the control vs 1 dB for the KX-R Twenty. The optimal S/N ratio can be maintained by choosing parts with close tolerances. You have more control over part values. Typical volume potentiometers are not accurate over their entire range often resulting in an increase in noise and/or channel imbalance.

mrkaic's picture

Thank you for an exhaustive and informative answer. So, if I understand you correctly, the bank of 46 resistors essentially selects the closed loop gain -- like the resistors in an op amp circuit?

Could this work with a digital potentiometer? Those can give very close tolerances and even more choices that a bank of resistors.

Indydan's picture

Would it not have been better to test the preamp with an Ayre power amplifier? Of course the Shindo preamp will sound better with a Shindo power amp, DOH!

Can generalizations be made when the Ayre was tested with 50 year old speakers?

I wish Mr. Hansen was still around. He would have surely commented on the review.

johnnythunder's picture

As much as I love Art's writing and reviews, I agree with Indydan about this somewhat flawed approach to reviewing these state of the art components in a "vintage" reference system. I think it's an interesting angle to hear how these components blend together but it's sort of a tangental idea not one for a comprehensive review. It should be classified as a separate type of review - this mix of old and new. How do AR or KLH bookshelf speakers stack up against today's ELACs or KEFs or NOLAs or JOSEPHS? that would be interesting to read...but speakers designed to be used with low powered tube amps powered by a new amp is not the same thing...

mrkaic's picture

Johnny, what is your problem?

Mr. Dudley writes SUBJECTIVE reviews, so he can pair any components he wants and evaluate them by LISTENING. [Gee, I wonder where the master title of his editorials comes from? :)] His approach is not scientific.

If you want rigor, read JS'a measurements.

johnnythunder's picture

and especially not attacking Art D. who is a national treasure and who's ears and musical taste are impeccable. He's one of my favorite magazine writers. My issue was the odd mismatch of amp and speakers as the only point of comparison in the review of the amp. I am not in the double blind comparison camp or a skeptic about tweaks, cables or AC power enhancements. I simply felt that the Ayre should ALSO best be paired with a modern state of the art speaker that it was obviously designed for. I wouldn't be stating any of this if the review was of a modern state of the art push pull or single ended tube amp used w his Altecs. So this has nothing to do with science or rigor but of what is in my opinion a slightly incomplete way of assessing this particular piece of equipment. It's just my opinion in this instance.

mrkaic's picture

You see, I'm a passionate objectivist and rely on measurements first and foremost. However, if the genre of a piece is subjectivist, then anything goes. Including pairing amps and speakers that are not from same period of audio development.

So, I guess we see this issue somewhat differently.

CG's picture

Kind of late to reply...

I was motivated to reread the review based on Jim Austin's recent comparison of this preamp to a PS Audio unit.

Personally, I straddle the objectivity camp and the subjectivist camp. Here's why...

In my day job (nothing to do with audio), I am exposed to more electrical engineering measurements than any reasonable person should ever be subject to. What I have found is that it's very, very easy to oversimplify any form of analysis by relying on a rote set of measurements, industry standards or not. Very often, they don't really tell the whole story. That isn't to say that you can't invent tests that tell you more, but that's not the usual modus operandi, at least until something breaks.

So, to me, measurements are often - not always - what my geometry teacher used to call necessary but possibly insufficient conditions." In other words, they may not tell the whole story.

But, if that's not your belief set, I'm not here to argue with you or dismiss your philosophy. Just explaining where I am coming from.

That said, you do raise a really good question. (Whether you knew it or not!)

Why are all the pieces of audio equipment tested in isolation, by themselves, under the most pristine test conditions possible? Why are they not tested when used in conjunction with other gear or an entire system? Doing this all in isolation is hardly a "sufficient condition."

The list of possible system interactions between components is far, far too long to even compile here. That's even when excluding the acoustic performance of the loudspeakers in concert with the room. Just the numbers of possible electronic interactions is staggering.

Yeah, I know it'd be very labor and time intensive. But that might be preferable to a set of tests that tell you just enough to lull you into the idea that you know what an audio component will do. That's why trying a new piece in your own system and deciding whether you like the sound might be a way better approach.

Any thoughts?

villager56's picture

Hi John,
The measurements reported for this unit appear very similar to the measurements that you reported for the K-5xeMP in 2011. Would you kindly add a few words comparing the measurements of these two units and how the new technologies are reflected in the measurements of the latest model? Thanks!