Pass Laboratories XA25 power amplifier Page 2

The ancient poetry of El Din's singing is driven and supported by playing of the oud, and the first thing I noticed was how full and authentically wooden his instrument sounded. The second thing I noticed was how the XA25 revealed the vibrations in the spaces between the oud's string courses, sound holes, and soundboard. I could sense the XA25 reproducing a boiling, stream-like continuum of acoustic energy.

This is what high-quality audio is supposed to do: make the energy coming out of the speakers resemble the energy that went into the microphones, so that wooden instruments sound exactly like the vibrating wood they are. The Pass Labs XA25 made the DeVore O/93s seem less like rattling boxes, more like projectors of aural holograms.

As I played more music through the Pass-DeVore combination, I began to realize that the XA25 is the most transparent amplifier I've ever heard. I also began to wonder if the reason it took so long to break in wasn't just a break-in thing—it was the unusualness of its transparency that was breaking me in.

Late one rainy night, listening to some Slovenian tango—the Mascara Quartet's Barco Negro (LP, Sazas Biem VVE LP 001)—I was reminded of the first thing I'd noticed about the XA25's sound: the intense presence of the midrange. The song "Barco Negro" (Black Boat) was first recorded in 1954, by the queen of fado, Am†lia Rodrigues. The Mascara's version, with singer Polona Udovic, is no match for the original, but it showed me how uniquely solid the XA25's midrange was. Udovic's voice felt strong and forward; male voices felt chestier, drums more corporeal. This midrange solidity wasn't subtle—the more I listened, the more I suspected it was having a psychoacoustic side effect of making the octave just below it (125–250Hz), as Irish Brother said, "thinner than normal."


The Mascara Quartet hails from Slovenia, but the dark melancholy and eccentric pacing of their music is pure Latin milonga, with overtones of downtown New York avant-garde. The excellent Pass-DeVore partnership displayed all the subtly striding rhythms and eccentric fluctuations of Mascara's milonga vanguarda.

Listening with the Stirling Broadcast LS3/5a V2
I'm currently so enamored of Stirling Broadcast's LS3/5a V2 speaker because, more than all other audio traits, I value accurate tone, vivid rendering of space, and realistic texture. The more instruments, singers, and rooms sound like themselves, the more the recording process reveals itself, and the more easily I can dream along with the music.

Dear Reader: If you can live with a pair of small, pipe-and-slippers British loudspeakers, the combo of Stirling LS3/5a V2s and Pass Labs XA25 was an enticing combination with all types of music, playing really big and dance-hall lively. Both Barco Negro and Lily of the Nile sounded more complete, full, whole, and natural than through the Magnepan .7s, KEF LS50s, Zu Audio Soul Supremes, or DeVore Orangutan O/93s.

Compared with the First Watt J2
The Pass Labs XA25 ($4900) puts out 25Wpc into 8 ohms. So does the First Watt J2 ($4000). (Both were designed by Nelson Pass.) Besides a heavier, more attractive case, the additional $900 buys you:

• an amp capable of putting as much as 50Wpc class-A (or 100Wpc class-AB) into a 2 ohm load like the Magnepan .7s (the First Watt J2 struggled with loads below 6 ohms);

• an amp that makes music with less richness of tone and less saturation of color than the First Watt J2, which shows me the different hue of each star in the night sky—the XA25 shows me the pulsating energies that fuel them; and

• what might be the most transparent amplifier available at any price.

Compared to the Line Magnetic LM-518 IA
The Pass Labs XA25 ($4900) and the Line Magnetic LM-518 IA integrated amplifier ($4450), the latter used only as a power amp via its pre-in jacks, made for a very interesting comparison—not only because I'm deeply fond of the LM-518's scintillating midrange and near-perfect high frequencies, but because this pair of 25-watters might be two of the most different-sounding amps I know.

When I removed the Pass Labs from the system and began listening to the Line Magnetic, all I could hear were the luminous note decays of Peiju Lien's pipa in "Le Luneux," from Transcending Continents & Memories: Medieval Europe Meets Traditional Chinese Meets Avante-Gard [sic] (LP, M•A Recordings M091A-V). This mix of French medieval, post-postmodern, organetto, hardingfele (Norwegian fiddle), percussion, and traditional Chinese pipa (a lute-like instrument) is surely one of producer, engineer, and M•A owner Todd Garfinkle's finest releases on levels both musical and sonic.

It had been a while. I'd forgotten just how grainless, present, and refined the LM-518's 845-tube highs could be, but I instantly recognized them as better than the XA25's. In fact, through the Stirling LS3/5a V2s, the top six octaves of the LM-518 pretty much define the type of sound I admire. (MOSFETs vs 845 bright-emitter tubes?)


After listening so long to the push-pull, solid-state XA25, abruptly switching to a single-ended tube amplifier like the LM-518 was disorienting—and intoxicating. My friend Sphere and I always pay attention to what we call the Sequence Effect: Our perceptions of the character of the component just switched to are dramatically affected by the sound of the component that immediately preceded it. With the LM-518 in the system, I listened to several complete albums before I could stop noticing the exquisiteness of the sounds emanating from the Stirling LS3/5a V2s. The LM-518 made music sound and feel less weighty and sinewy than the XA25. But in exchange, the LM-518 delivered infinite multitudes of refined, subtle contrasts.

The revealing nature of the XA25 helped me recognize the wildly different but equally revealing nature of the LM-518, as well as the transcending, hypnotizing time warps of Transcending Continents & Memories. The Pass XA25 and Stirling speakers let this exceptional recording sound achingly pure and refined. The LM-518 did less of that.

The LM-518 IA and XA25 threw equally enormous soundstages, but the quality of those soundstages was enormously different. The Pass's sound spaces were absolutely quiet and profoundly empty. With the Line Magnetic, spaces seemed less vacant, more grainy and hazy through the presence region. The LM-518's best trait was how its midrange seemed fantastically charged with the energy of players playing, and with lingering, vibrating sounds. The XA25 emphasized rhythm and vitality.

The Pass Labs XA25 is not subtle about what it does well. Partway through my listening for this review, I began to imagine how this amplifier could be audio's Salvator Mundi. Its divine transparency blesses and illuminates every aspect of the music it touches, enhancing the subtlest aspects of tone, texture, microdynamics, space, and atmosphere. Its midrange force makes rhythms stronger, and exposes the flesh and blood of players and singers.

Those are rare and important qualities, but still, the XA25 made me nervous—it took me a long time to grasp the essential character of its unique sound. Now, finally, I'm awed by how lucidly it renders music. Pass Laboratories' XA25 is reasonably priced, strong beyond its power rating, and positively revelatory. Classe A se você, por favor.

Pass Laboratories Inc.
13395 New Airport Road, Suite G
Auburn, CA 95602
(530) 878-5350

tonykaz's picture

Lately we've learned that High-End isn't Audiophile.

HighEnd is gear made for folks with mucho dinero, it has the smooth touch and has super high prices.

Audiophile gear ( my kind of gear ) is performance gear ( not built for prettiness ) but built with superior quality parts, understandings for what they do and proper placement in their circuits. Audiophile gear is built to perform musical magic, it's built by people that know how to create, and consistently deliver, Virtuosity. Is Mr.Reichert pointing out that Mr.Pass is one of those people? I think he is!

How many greats are there ? Pass, King, Curl, Had, D'agostino and probably a goodly number of others.

I'm say'n thanks for this XA25 Report, I'm glad Herb and peers like this design and I'm glad it's only $5,000. Maybe someone will swap their Fisher Reciever for it as it's certainly aimed at the dedicated & experienced Audiophile who can't live without the "increasing" thrills of musical discovery and still needs to preserve residual values. Pass stuff is very expensive to purchase "used" on eBay.

We have a reliable list of Recomended "Audiophile" componants from Herb Riechert and Steve Guttenberg !

I wonder if they could've discovered things like this Pass XA25 if they didn't already have a range of outstanding Loudspeaker transducers ?

This Amp Review and it's contextual detailing reveals the importance of having some sort of Guide to help navigate thru the gear selection process. Stereophile to the rescue

Tony in Michigan

jsch4297's picture

Tony is just a down to earth good ol' guy brett favre substance over style. He has it figured out and the other guys are about ignorant prettiness. Only empty style and no substance. Tony is lucky to be him and the other guys are rich suckers. Their heads are in the clouds and they only care about appearance.

Btw, I own $130K worth of audio gear, and I consider them High End in terms of there they sit in the product hierarchy. Components include the Pass xa60.8 mono blocks and the FirstWatt F7, audio research ref 6, 2-VAC preamps, 3-pairs new world sonus faber speakers, emm labs dacs, dynaudio speakers, focal utopia headphones. And those speakers are "oh so pretty..."

Tony, where do I fit into your little mutually exclusive world where you tell yourself people with more money are style over substance (while you're seated right in the sweet spot of humanity)? I recommend reading Carl Jung to specifically understand your own "shadow", and you can begin to pull yourself out of cave man thinking. Maybe sit back and listen for 2 or 3 years, don't give others' advice (because you're hurting them), and come back to the world a better man.

tonykaz's picture

You are the Audiophile type not the HighEnd type. Your gear is carefully selected for performance. Egads, you have the 60.8 Mono ! and a First Watt !!

My Social Wife would console your wife as another "Still Suffering" spouse having to share her peaceful home with "noisy" Stereo "Junk".

However, you're my kind of Man!!!

HighEnd is about Showy displays of Wealth. i.e. 97 Foot Hatteras Yacht with a Big Screen w/ "built-in" 7.1 Dolby surround sound Theater.

My comments are related to the various insights that Paul McGowan and Steve Gutenberg are "lately" sharing in their various YouTube daily Vlogs.

I, as a Retailer/Importer/manufacturer of Audio Gear sold HighEnd gear and I also sold to Audiophiles searching for performance. My Showy products far outnumbered my performance products. My best, top performance stuff were not the big sellers. Bose for example outsells LS3/5a by a factor of thousands to one ( maybe even greater ).

I'd say you went far out of your way to own outstanding Music stuff, you purchased plenty of it, you'd be somebody's very good customer.

As far as your $130,000 goes, it won't get you past the velvet rope when it comes to "Todays" HighEnd. The New Wilsons are $750,000. A Goldmund System will be closer to $2.500,000. HighEnd Turntable are costing $100,000, Arms are in the $30,000 range. My old pal Karen Sumner's Transparent Cable Systems range well over $200,000.

So, are you HighEnd or Audiophile?

Harry Pierson of TAS trained us to think that we're "High-End" but now, after following along with Steve Gutenberg's Video reports and Paul McGowan's thoughts I'll conclude that we're Audiophiles.

The times are changing, Audiophiles have the High Ground in Performance & Value.

It's just a matter of terminology.

Tony in Michigan

jsch4297's picture

Although I'm flattered, you're creating imaginary segments of people, then applying an imaginary competition between those segments in which your tribe of audiophiles has the "higher ground". I"m not in your tribe.

There's also no "velvet rope of high end". You just made it up. More imaginary segmenting. And if there was (which there isn't), you just moved it out far enough my situation feel "oh so poor and ordinary". Luckily my brain isn't wired like that.

Lastly, if someone has a $750k burmeister system in their yacht that their assistant ordered, i don't see any reason to judge that person on any grounds. Whether it's higher ground, lower ground, value showiness, non-audiophile. It's all just to try and make your own situation seem less desperate. I'm sure they like music as much as anyone else on the planet.

Now, you do peddle products for a living and you've probably consumed between 20,000 to 30,000 hours of television in your lifetime so I do understand how your thinking came to be.

tonykaz's picture

I'm Auto Industry.

Surely you've noticed the "High" side of Auto stuff !

There certainly is a Velvet Rope in Audio's HighEnd. Try to get an Audition of the Goldmund Store in Palm Beach Florida. You probably aren't a candidate to get those "Invites".

As far as me "peddle" products, that was the middle 1980s, I represented JVC, HarmonKardon, Wilson, VPI, PS Audio, Monster, Theil, Elecrocompaniet and every Turntable Manufacturer except Sota . I wanted to have Threshold stuff but they wouldn't or couldn't put their stuff in my Operation. I was offered Levinson but didn't like their gear compared to Electrocompaniet.

I left the Audio "High-End" Importing, Retailing and Manufacturer as CDs became the new format. I returned to General Motors work as a Manufacturing-Plant traveling Troubleshooter.

I've been long gone from all personal Audio ( except the Automotive Dashboard Radio / Music Systems stuff ) until I ran into Tyll & Steve G. at RMAF 2011. They recommended Schiit & Sennheiser which I purchased.
Now, I'm considering a "Retirement" Music System with enough build & design quality to do a nice job of playing Chad Kassem's new Releases which is why I reading Stereophile and XA Amplifier Commentaries.
I'm leaning to PS Audio because of BHKing, K.Smith, Arnie Nudel rip and Paul McGowan's upcoming Loudspeaker Releases and PS Audio's philosophy of Power Plant designs.
I'm also a fan of Kevin Deal and his Chinesium Tube Amps.
I'm kind-of inspired by those lads that stuck-it-out in Audio and lived to write about all of it.

I try not to flatter, I try to be analytical.

Tony in Michigan

ps. the Quality of the Music being released ( re-released ) and the beautiful playback from Digital Players is justifying my Investment in a Music System. I'm not going back to a large room filled with Vinyl.

rschryer's picture

Oh Tony, Tony, Tony.

Remember when we were stereophiles? Life was simpler then. Now you're getting yourself in trouble with all this high-end/audiophile nonsense.

Everyone's a stereophile, so nobody feels excluded. It's the great unifier.

Come back to the stereophile fold, Tony, away from the high-end/audiophile hullabaloo. It's safe here, and all tribes are welcome.

tonykaz's picture

Of course your right !

I'm sort of falling into agreement with Paul McGowan in his philosophy of Audiophile gear being purpose built to Audiophile Levels of performance, kinda the way sports cars are built.

I'll return to your Editorial to refresh but I'm appreciative of what PS Audio is doing nowadays. PS Audio was the First Product line I carried as I launched into the Audio Industry ( 4 Decades Ago ).

We ( my partner & I ) kinda loved Paul and Stan.

I'm also liking the beautiful releases from outfits like Kassem, Chesky and so on.

We are getting the nicest recordings NOW, I want gear thats been designed to play it properly. I'm thinking that PS is the outfit making it all from the PowerPlant to Player to DAC to Pre to Amps to Loudspeakers with Active Servo Woofers.

One Stop Shopping, like buying Linn/Naim in the old days.

Still, I won't forget Schryer and your contributions.

Tony in Michigan ( switching from Cheeseburgers to Rice )

ps. My Cardiologist says that I might have another 3 Decades needing a good life plan. Fingers crossed!

rschryer's picture

A: I'm switching from cheeseburgers to rice.

OTOH, PS Audio does seem to be making a lot of tasty-sounding gear.

Thanks for the kind words, Tony; I won't forget your contributions, either.

tonykaz's picture

Loudness is more than a complete thought, does that make it a sentence?

And that brings me back to what I'm seeing now-a-days : and I'm meaning "just-now-a-days"!!!

Audiophiles are producing their own dam recordings and plenty of em.

That is what justifies the Purchase of high performing Audio Gear.

Back when Loudness was built into everything ( because people were playing their music during "Drive Time" and the "Drive Time" meant the listening room had 75db ambient noise floors, the Music needed to drown out the dam noise.


Now, with the Smart Phone becoming the preferred Music Source of our most important Customers who are trending to use the supplied white wired ear phones ( or the wireless in-ear thingys from Apple ), we'll be getting sensibly recorded & mastered Music.

We Win !!!

Reference Recordings and their type of Vinyl was the Basis of my being in the Music Business. Now that level of released Recordings will drive a whole new generation of Buying Audiophiles ( or Stereophiles , like us ).

Tony in Michigan

ps. now we have to make all this accessible to the other half of the population, the ones with the checkbooks.

Glotz's picture

I grew up into being 'audiophile' when you were in the thick of it. Your insights really ring true, and the direction of the industry- the most refreshing and insightful. I get what you were saying about entry level being $5000 for this amp in this market. It is worth it (without hearing it), but the entire industry seems to be skewed up 50% because the market bears it on the extreme end, and modern machining costs and the need for continued innovation is required from manufacturers. PS Audio is a great example, and the Stellar series would appear to be their very answer to your (and mine) question of value in the middle tier of affordable range. There seems to be some serious reflections on inflation in the last 20-30 years that may seem justified, but really creates a stark picture of the yawning gap between high- and middle-class toys these days.

There is much of what you speak that gives me hope, even though the small brick and mortars of the 80's and 90's are gone.

I didn't find that you were passing judgment others that can afford it, but let's be real- $250,000 for a stereo system is not normal. For 99% of society... One would have to own $500k in cars for that to even be rational in most families, not covering multi-million dollar homes, etc. This is not what most music-loving, audio component-interested folk are buying. We still dream and relish the test drives.

Do I still love reading about the ultra high-end? Yes! All of the time? NOOOO.

Ortofan's picture

... bias circuit have to interpret continuous high-power, high-frequency tones as a fault?
Does any other amp have this limitation?

windansea's picture

I'd have liked to hear how the Pass amp fared against the PS Audio M700s with the maggies. Sure wish the reviewers would do a little bit of ABX to enhance their credibility.

Herb Reichert's picture

my hand is shaking as I answer your question . . . . I have written at length about the Maggie .7s with the Bel Canto Ref.e600Ms which I use all the time in reviews because I believe them to be articulate powerful sounding amplifiers - which suit my taste very nicely but . . . .high bias class-A is still . . . well you know :-)

tonykaz's picture

On this matter of Comparisons....

Can or will you offer an opinion about the earlier Pass designs ? even the 555 Adcom ?

Has N.Pass built trust from all the way back ?

I tried to sell the Threshold stuff but they couldn't let me have it. darn.

Tony in Michigan

Herb Reichert's picture

right there on the same musical mountain with Chuck Berry, Elvis, Lead Belly, and John Lennon. In fact, N. Pass may be the John Lennon of amp designers

tonykaz's picture

are you suggesting : once loved but dead?

Thanks for answering,

Tony in Michigan

Herb Reichert's picture

Nelson is the Robert Zimmerman of amp designers

tonykaz's picture

isn't it?

I took all of his music on a long road trip and ended up listening to Paul Harvey and DX, for gods sake. I deleted most of his releases, when I returned home. I had fond ( smoke enhanced ) memories of "Bobby" that don't play well in a Sober Today. I wish they did, we need the old Bobby Dylan now that Orangeman is in Washington.

Tony in Michigan

Glotz's picture

What a great correction with impeccable timing..!

windansea's picture

thanks for the reply, I'll check out your Bel Canto review!

BTW, with Class A every review ought to mention the heat level after a few hours of listening. (for those of us in warm areas)

Herb Reichert's picture

"Before performing any tests, I ran it at one-third its clipping power (see later) into 8 ohms for an hour. At the end of that time, the top panel was warm, at 102.3°F (39°C), and the heatsink fins were hotter, at 122.2°F (50.1°C)." Its in the measurements section

RDSChicago's picture


Great article. I have a pair of Kent’s 57’s and love them. Does the FW J2 have enough juice to drive them as well as or close to the X25? I read somewhere that the J2’s impedance curve may not be a good match. I have a J2 which I’m currently using to drive a pair of Linkwitz Orion’s tweeters. I also have a pair of Nelson’s Aleph 0 monoblocks driving the Orion’s mids. I haven’t tried either amp yet with the Quad’s and would welcome and appreciate your thoughts.

BTW, in a Quad amp shootout a few years back with Wyatt, Chesky and Lavorgna, the Rogue Atlas Magnum came in second place after the ASR Emitter. I’m driving the Quad’s with the Rogue Cronus Magnum as I write this email and they are sounding quite excellent.


RDS in Chicago

georgehifi's picture

Manufacture: Giving us the illusion that this amp can double wattage for each halving of load impedance.
8ohms 25w
4ohms 50w

Stereophile tests:@.1% thd No where near the doubling act.
8ohms 80w
4ohms 130w

Then manufacturer amended test at .01% still not doubling!!
8ohms 35w
4ohms 55w

When are manufacturers going to stop trying to fool readers with understating the 8ohm wattage spec to make the 4ohm look like the amp can double for each halving of load impedance.

Cheers George

tonykaz's picture

isn't it just ohm's law ?

Is it the Amperage increasing as Impedance decreases.

Lower resistance i.e. 4 ohms or 2 ohms would require the Amp to increase the current to nearly double or more to maintain the same level of listening.

The amount of Energy should remain the same.

Tony in Michigan

ps. the Marketing Magicians ....

supamark's picture

Pass states that the XA25 puts out 25W into 8 Ohms, 50W into 4 Ohms, and 50W class A into either load. The amp easily exceeded the published specs into either load. This is, literally, the silliest complaint I've ever read about an audio component.

Maybe take a look at the $33k Jadis monoblocks reviewed elsewhere in this issue that can't even come close to half their rated output (and were specially modified by the mfg for the review) - now that's shifty (and shitty).

Jason Victor Serinus's picture

The Jadis monoblocks were not specially modified by the manufacturer for the review. A choice of tubes is available for the amps, and Jadis chose the tubes they felt would work best.

I hope that someday, I'll get a chance to hear these monoblocks with the Alexia 2s. I've been listening to them with Pass XA 200.8 Class A monoblocks, and their impedance curve in the bass, which is far amp friendly than the bass impedance curve in the Alexia 1s, is making a major difference.

supamark's picture

from JA's power measurements section:

"...I was puzzled by these results, as they suggest that the internal strapping of the Jadis's output transformer had been set up not for "4–8 ohms," as the distributor's representative had assured Jason Serinus, but for a lower impedance. Indeed, when I removed the JA200 Mk.II's bottom plate and compared the connections with those printed in the manual, it became apparent that this sample of the amplifier had been optimized for a 1 ohm load."

So, yeah, Jadis mod'd the amps to work with your speakers and like the pro he is JA figured it out - this testing, by the way, is one of the things that puts Stereophile well above rags like TAS. Pretty surprised JA didn't tell you, but not surprised the Jadis rep (a salesperson) lied about it.

John Atkinson's picture
supamark wrote:
"it became apparent that this sample of the amplifier had been optimized for a 1 ohm load." - JA

So, yeah, Jadis mod'd the amps to work with your speakers.

You can see the output transformer tap wiring in the photo on the second page of the Jadis review:

supamark wrote:
pretty surprised JA didn't tell you.

I did tell Jason but not until after he had submitted his review text. Stereophile's reviewers don't see the measurements or my thoughts on the products until after they have written the review. That is so what they write about sound quality is not influenced by seeing the measurements. I take my hat off to them for not being intimidated by this.

John Atkinson
Editor, Stereophile

Glotz's picture

I am sure that the Jadis dealer would also consult the owner to find out what speakers they are using.. this is nothing new for companies like these... for the past 30 years.

supamark's picture

the point remains, the rep told JVS that the amps were unmodified, after in fact modifying the amps to get a better review - this is shady behavior. Whether they'd do this for a customer is immaterial - they straight up lied to the reviewer, what makes you think this is isolated behavior? I doubt this was done without Jadis' knowledge. Hell, because of the mod, there's no way to know if the Jadis is even capable of anything like its rated output (I suspect not).

On a side note, Jadis should have requested AD for this review as he's much closer to their natural market.

Glotz's picture

It is NOT immaterial either.. The dealer has been the point of contact to assist customers for decades. If there was an issue with communication, it really seems like they are trying to pull a fast one on their readership... but who really cares?

If I told the dealer I have a 2 ohm speakers, they would consult Jadis, and apply the correct parts and values. These values for the correct load in ohms is something that most if not all dealer perform for their customers, specifically for the speaker load they are pushing.

This is akin to a phono stage manufacturer swapping out the correct resistors for the values that their cartridge needs. MC and MM, as you know, will require very different values and settings, depending on the application. Big whup there was a communication issue.

Lastly, it is THEIR determination who reviews what... if it seems like a mis-match for JVS and his equipment... tough! This is all about seeing what an amp can do in a variety of scenarios. He wanted to review it, and I'm sure it was a learning experience (which is a good thing). Perhaps JVS needs more speakers on hand, but that's my only criticism.

Lasty, what are you in this hobby for? To point out collusion and a lack of objectivity? That is utter tripe.

These reviews are a guidepost to listeners to find the correct match for their systems and audition a product that suits them. This is not some absolute establishment of value and hierarchical control of the market. Even Recommended Components is a list created by individual people and their opinions. They are not telling you what to buy... simply what to audition.

This makes your stance seem like much ado about nothing... Go find another mag if you're so insulted about this issue?

Ali's picture

Thanks for the review and I strongly recommend also trying to listen to Audio Research Ref6/GS150 Pre/Power combination. Listening to them through my Wilson Sasha 2 connected to GS150 8 Ohm tab and comparing them with several other SET amplifier, transparency champ, and also Pass own 250wat integrated recently, the amount of transparency, low coloration, dynamic and musicality of AR Ref6/GS150 was beyond whatever amplification system that I have ever had in my room. Not to mention I am a SET guy and when ordered push/pull design with 8 huge tube in amp and another 6 tube in pre, I was quite doubtful of getting any transparency at all let alone being better than the other bests. Give them a try and you will see. But of course the price...

tonykaz's picture

Steve Guttenberg is at work today.

Tony in Michigan

georgehifi's picture

"The amount of Energy should remain the same."
Submitted by tonykaz on February 4, 2018 - 5:04am

Yes the close to doubling act from 8 to 4ohms is an indication of an amps ability to deliver current from it's output stage and power supply. In this case the amp can't do it as the test show, but it's advertising does look like it can, because of the understated 8ohm wattage, to make the 4ohm look like it's doubling, it's not that hard to grasp.

Cheers George

deckeda's picture

... that this sort of design (and, of course, from N. PASS) still exists in 2018.

And down on the main home page here, right below it, is a piece on a Jadis amp reboot.

What ... is it the 1990s again?

Kudos, thanks, and let's shut up and listen.

gizmo101's picture

Took weeks to break-in and the sound changed with different speaker cables?! I supposed you have to say so to make yourself sound like an audiophile with golden ears!

High quality amps are being tested for days before passing the final test and inspection. By then, it would have been fully broken-in, if there is such a thing!

Glotz's picture

Every combination of amp and speaker (and cable) sounds different.

Almost every component needs break-in. This is not new, nor is it bullshit.

FredisDead's picture

You made a reference to the Pass XA-25 making your DeVores sound halographic and "less like rattling boxes". I also note you are no longer using the Primaluma preamp you were once so enamored of. I own an ARC Ref6 with an ARC Ref150se and DeVore O/93's. I suspect this request is not something you will try but I would submit that your choices of preamps and cabling have been less than optimum for the O/93's and that if you were to humor me by borrowing an ARC Ref6 with your choice of amp in the same quality range as the Pass, tube or ss, and humor me further by using Cardas Clear xlr between the preamp and amp and Cardas Clear speaker cable you would see jusr how halographic and non-point source the O/93's can be. I speak only from first hand trial and error and I have no industry connections. But please, despite what John DeVore recommends, Auditorium 23 is NOT the best speaker cable for the 0/93's and the magic of the ARC Ref6 per Mikey's review in helping to create a wide deep and halographic soundstage is undeniable. I have been following your reviews closely since you came on-board with Stereophile and you seem to select expensive analog source gear and devote less resources to preamps and cabling. Please-hear for yourself the full potential of the brilliantly designed DeVore O/93's!

Herb Reichert's picture

I am always looking for that real-world afforadble 'sweet spot' the knee of the price-performance curve. I also try to describe whole systems that normal people could actually assemble.

As for the expensive analogue front ends? I can't help it I love exotic transducers especially cartridges and headphones.

As for the PrimaLuna Prologue preamp - we are still together and in love.

FredisDead's picture

"I also try to describe whole systems that normal people could actually assemble."
I know what you meant Herb but have to chuckle. What makes the Ref6 at around $15,000 a preamp that normal people can't actually assemble when you have a pair of DeVore O/93's that with tax (they can't be bought mail-order as far as I know) cost right around $9400? You own a turntable that cost $11,500 before adding the $3,000 cartridge as you stated;
"The Giro G9 is the Giro turntable bundled with the 9W2 9" tonearm. The package costs $10,000 without phono cable. Happily, my Giro G9 review sample came with AMG's Teatro moving-coil cartridge ($2750) and Reference phono cable ($1500)"
My point being; it's a matter of resource allocation rather than being "a man of the people" by which you no doubt refer to as "normal people".
My original post remains right on point-I am suggesting that just for grins, you ought to try some resource re-allocation. I too lust after that lovely Giro AMG Giro G9 and would take it a heartbeat over my VPI Prime that cost less than half of its price, and would love your choice of cartridge over my ~$1000 Ortofon Quintet Black and ~$1,000 Benz Gliders (2) on their third Peter Lederman rebuilds.
I am suggesting that your going lean on the carburetor when it comes to preamp and cabling and rich on the source-although a basic concept I ascribe to in general-does not pay off handsomely in the particular case of the DeVore O/93's. I did not notice that before my post, someone else had already posted about the magical combination of the ARC Ref6 and ARC GS150 (the exact same amp as mine with a glitzier front). I assure you it was a complete coincidence but should tell you something.

Herb Reichert's picture

Thank you FredisDead for reading my stories so carefully. As for today, the only analogue products I own are my Linn LP12 Valhalla (soon to be a Hercules) and the SME M2-9 tonearm attached to it; also a 1957 Thorens TD124 turntable and the Abyss AB1 tonearm attached to it. I also own a cool pile of old Shure, Ortofon, Dyavector, EMIA and Denon cartridges and SUTs. All high quality but affordable stuff. Left to my own audiophile devices, I am at heart a DIY rat rod sort of guy.

jorgen's picture

Dear Herb,
Thanks for your review of the XA25. For a long time now I have been in the market for the very best amp for my Quad ESL 63. Do you think the XA25 would do the same wonders with a refurbished Quad ESL 63 as it did with the ESL 57?

Herb Reichert's picture

I have very little experience with the 63s. But I bet it might !

give it a try

peace and flowering trees

Herb Reichert's picture

I have very little experience with the 63s. But I bet it might !

give it a try

peace and flowering trees

gweedoargus's picture

In your opinion, can the pass labs xa25 sufficiently power the BW 804 d3s? Any impressions on the pairing would be useful also.

AnalogueFan's picture

Hi, I ask the same, similarly, but reviewers rarely answer.

AnalogueFan's picture

In your opinion, can the Pass Labs XA25 sufficiently feed or power the WB (Wilson Benesch) Chimera .?
Any impression on the pairing would also be helpful.
Thanks in advance, although I know that reviewers rarely respond.
But. In this case the ampere, damping factor, 4 ohms power rating, Idle power draw, and other specifications look good.
Kind regards,