Pass Labs Class-A Monoblock Preview

Robert Harley -- Tue, 06/24/2008 - 11:45

In Issue 183, Neil Gader reviews the new Pass Labs INT-150, a 150Wpc integrated amplifier. This is Pass' first integrated amp.

I have the Pass XA-100.5 in my system right now. These are 100Wpc pure Class-A monoblocks.

I read Neil’s description of the INT-150 with frequent head-nods of recognition at his description of the amplifier’s sound. There must be a strong family resemblance between the INT-150 and the XA-100.5 I’ve been listening to through Wilson Audio Alexandria X-2 Series 2 loudspeakers. Neil’s descriptors “ease and fluidity” and “sweetness” were particularly striking, because that’s exactly what I hear from the XA-1005s. Music reproduced through the XA-100.5s has an astonishing beauty of timbre, with tremendous liquidity and ease. Significantly, it achieves these qualities by apparently reducing, rather than adding, colorations. This amplifier has a warm and inviting sound that is simultaneously relaxing and exhilarating; the former quality is a result of the sense of warmth and ease, the latter from the amplifier’s explosive dynamics and high resolution.

My full review of the XA-100.5 will appear in issue 184.

Marba -- Tue, 06/24/2008 - 14:44

robert_harley6 wrote:
I have the Pass XA-100.5 in my system right now. These are 100Wpc pure Class-A monoblocks.

I’ve been listening to through Wilson Audio Alexandria X-2 Series 2 loudspeakers. Neil’s descriptors “ease and fluidity” and “sweetness” were particularly striking,

My full review of the XA-100.5 will appear in issue 184.

How does it compare to the DMA 360s?

sacduser -- Mon, 06/30/2008 - 01:00

If they sound even better than the XA-100, which I've auditioned thoroughly, they should be mighty smiting.

The old XA has a gorgeous sense of musical flow and low-level continuity. Must be that lack of crossover distortion due to the Class A circuit. Very SET, in the best sense of the word. Sounds like the musicians are playing directly FOR you.

Not the greenest of amps though. In fact the XA series guzzles torrents of watts in order to produce those delicate and elegant musical result. But it will be worth it. Factor the cost of electricity in the final price.

The XA whacks harder dynamically than regular Class A amps, but not as freely as the X.5 Pass amps. Wonder if it does better with a 4 ohm load than the previous XA series. Although I disqualified the XA's as they could not drive my 4 ohm Magicos, I think I'm still in love with them.

I'm keen to find out what's new about the .5 version. What improvements does it offer over the old XA's?

Robert Harley -- Mon, 06/30/2008 - 11:26

The new Pass amplifiers are much more efficient (20% more if I recall correctly), and don't seem to run excessively hot for a pure Class-A amplifier. I once lived with Mark Levinson No.20.5 amplifiers and they were room heaters (and didn't sound good until fully warmed-up).

The Pass and Spectral DMA-360 amplifiers are both beautiful, but in different ways. The Spectrals have a bigger and better-defined soundstage (no suprise there), and the Pass amps have more bottom-end weight and warmth.

Marba -- Mon, 06/30/2008 - 15:36

robert_harley6 wrote:The new Pass amplifiers are much more efficient (20% more if I recall correctly), and don't seem to run excessively hot for a pure Class-A amplifier. I once lived with Mark Levinson No.20.5 amplifiers and they were room heaters (and didn't sound good until fully warmed-up).

The Pass and Spectral DMA-360 amplifiers are both beautiful, but in different ways. The Spectrals have a bigger and better-defined soundstage (no suprise there), and the Pass amps have more bottom-end weight and warmth.

Tube warmth or bloat?

Robert Harley -- Thu, 07/03/2008 - 14:21

The XA-100.5 doesn't sound warm and fat the way a tubed amplifier does, but neither is it dry and astringent in the mid-bass the way most solid-state amplifiers sound.

Marba -- Fri, 07/04/2008 - 06:04

robert_harley6 wrote:The XA-100.5 doesn't sound warm and fat the way a tubed amplifier does, but neither is it dry and astringent in the mid-bass the way most solid-state amplifiers sound.

To remedy dryness we should use tubed CDP od preamp?

Robert Harley -- Sat, 07/05/2008 - 12:40

I'm not sure I understand you question, Marba

dazzdax -- Sat, 07/05/2008 - 13:30

Hi Robert, could you describe the differences in sound between the Mark Levinson ML 20.5/20.6 and the Pass XA series? Thank you.

Chris

Robert Harley -- Sun, 07/06/2008 - 22:01

It's been 17 years since I had the Mark Levinson 20.5 amplifiers, with very different sources, loudspeakers, and cables, not to mention a different room. Nonetheless, Class-A amplifiers seem to have a directness of expression and timbral purity rarely heard in Class-A/B amplifiers. These are the qualities I remember from the No.20.5s, and also hear from the Pass XA-100.5s.

Marba -- Tue, 07/08/2008 - 04:57

robert_harley6 wrote:I'm not sure I understand you question, Marba

It's more a coment, one should use tube preamp to deal with dryness

Robert Harley -- Tue, 07/08/2008 - 13:43

Marba suggests using a tubed preamplifier to counteract the dryness often heard in solid-state amplifiers. Although this might produce a more musical system, I think a better approach is to choose a solid-state amplifier that doesn't sound dry to begin with.

This raises the larger question of how best to build a system. The best approach is to choose components that don't veer so far from neutrality that they require matching the other components that veer equally far from neutrality, but in the opposite direction. A system built on counteracting one set of colorations in one component with an equal but opposite set of colorations in another component is like a house of cards; make one change and the whole thing falls apart.

Marba -- Wed, 07/09/2008 - 03:26

robert_harley6 wrote:Marba suggests using a tubed preamplifier to counteract the dryness often heard in solid-state amplifiers. Although this might produce a more musical system, I think a better approach is to choose a solid-state amplifier that doesn't sound dry to begin with.

This raises the larger question of how best to build a system. The best approach is to choose components that don't veer so far from neutrality that they require matching the other components that veer equally far from neutrality, but in the opposite direction. A system built on counteracting one set of colorations in one component with an equal but opposite set of colorations in another component is like a house of cards; make one change and the whole thing falls apart.

When you set off to build a neutral system, which is impossible due to the interactions between components, cables, speakers, room, you are dealing with tradeoffs.
Even the same music played by the same group of people in different venues doesn't sound the same.

Syd -- Wed, 07/09/2008 - 21:59

I don't think I agree with this. If one has as a goal to build a system that is neutral to the "source", then you can choose your components with that goal in mind. Not all audiophiles have this goal, and may have different goals for how therse system should sound which in turn drives there selection of components.

I for one have built a system whose goal is to be as neutral to the source as possible (within my budget) and have been very satisfied with the results.

Robert Harley -- Thu, 07/10/2008 - 10:24

Of course, system matching is an art that balances trade-offs to achive the most neutral final result. My point is that it's better to build a system on a foundation of neutral components rather than accepting high colorations in one component with the idea that you can correct it by matching it with another component with the opposite colorations.

sheepherder -- Thu, 07/10/2008 - 11:48

Since we all hear things differently one man's neutral maybe another woman's dry!

Would be interesting if the reviewers for TAS and Playback all had hearing tests and then had them published.

Exposure to loud noises, gender, age and genetics would all come into play.

My dogs have selective hearing ie they will ignore a come by or lie down
but always hear the call for dinner even on the other side of my 1000 acres.

To reviewers suffer from selective hearing?

Sheepherder
Shenandoah Valley, VA

Syd -- Thu, 07/10/2008 - 13:21

robert_harley6 wrote:Of course, system matching is an art that balances trade-offs to achive the most neutral final result. My point is that it's better to build a system on a foundation of neutral components rather than accepting high colorations in one component with the idea that you can correct it by matching it with another component with the opposite colorations.

Robert - If this post was directed at me, we are in agreement as that was the point I was trying to make as well, and in my opinion, have succeeded in doing so with my own system. What I was disagreeing with was Marba's comment on it being impossible to build a neutral system.

Marba -- Fri, 07/11/2008 - 06:54

Syd wrote:I don't think I agree with this. If one has as a goal to build a system that is neutral to the "source", then you can choose your components with that goal in mind. Not all audiophiles have this goal, and may have different goals for how therse system should sound which in turn drives there selection of components.

I for one have built a system whose goal is to be as neutral to the source as possible (within my budget) and have been very satisfied with the results.

So what is in your "budget" neutral system?

I have ML 32S and 33H, EGG W the Nine, Metronome T2i sig and K-S cables

Syd -- Fri, 07/11/2008 - 09:20

You have an excellent system Marba. Here is a link to a thread that describes my system. The list of components is in the middle of my first post.
http://forums.avguide.com/viewtopic.php?t=4123

hce4 -- Tue, 12/16/2008 - 14:18

Robert Harley,
I was wondering what preamp and source you utilized with the XA100.5 monoblock amplifiers you reviewed?  
I was also wondering if TAS has plans for reviewing Pass Labs XP10 or XP20 preamps or if you yourself have listened to these preamps?  They are said to be much improved over their past generations, and I'd be interested to hear you impressions, especially in comparison to your reference Spectral electronics.
Thank you! 

Robert Harley -- Thu, 12/18/2008 - 15:48

Anthony Cordesman has just completed a review of the XP20 preamp. He also writes about the XA150.5 monoblocks, the more powerful versions of the amplifiers I recently reviewed.
When I listened to the XA100.5, I used it with a Mark Levinson No.326S and a Spectral DMC-30SS.
In my review of the Spectral system (February issue, which mails to subscribers next Tuesday), I compare the XA100.5 with the DMA-360. They are quite different sounding, with each beautiful in its own way.

Peter Ayer (not verified) -- Mon, 01/05/2009 - 19:10

Hello Robert,
I very much enjoyed your review of the Pass XA100.5 and read that Anthony Cordesman just reviewed the XP20 and maybe the XA160.5 amps (I'm not aware of an XA150.5).  When will his review appear in TAS?  Information about the reviewers' room dimensions and other system components during the review would be helpful to the reader.  Does TAS have any plans to do a manufacturer feature on Pass Labs?  The ones on Magico and Spectral and Wilson were superb. Thank you for your great magazine.

Peter Ayer -- Thu, 01/08/2009 - 11:17

When will Anthony Cordesman's review of the Pass XP-20 and XA 160.5 appear in TAS?  Does TAS plan on doing a profile/interview of Pass Labs the way they did of Wilson, Spectral and Magico?  Those were very interesting features.

Mike999 -- Fri, 12/19/2008 - 23:39

Hi Mr Harley
What were the findings of Mr Cordesman towards the amps?
When may we expect the review to be published?
In your opinion, will they match well with a pair of Wilson W/P 8s? If not, what in your expert opinion will?
Thanks very much.

Robert Harley -- Mon, 01/12/2009 - 15:44

Anthony Cordesman's review of the X20 preamp and XA160.5 amplifiers (along with my interview with Nelson Pass) will appear in the April/May issue, which mails to subscribers at the end of February.
 
My experience is limited to the XA100.5, which I used to drive the Wilson X-2. Based on that auditioning, the Pass amplifiers would be an excellent choice.

jmohd (not verified) -- Sat, 03/28/2009 - 09:35

Mr Harley,
 
I'm thinking on changing my Classe Ca301 amp to Pass Labs.
Before I use to drive Thiel 2.4 with the Classe.
Now, i've change my speaker to Harbeth Super5 and the near future may be to M40.1. 
What's your views on XA60.5 and also X250.5?
 
 
Rgds and thanks

Robert Harley -- Tue, 03/31/2009 - 14:48

I have not heard any of the other amplifiers in the XA-line, but know that they all use the same input and driver circuitry as well as the same output transistors. The differences are purely of scale; the more powerful amplifiers have larger power supplies, more output transistors, and bigger heat sinks. I would expect them to sound very close. It's been true, at least in some lines of amplifiers, that the lower-powered units sounded sweeter.

antono yuwono (not verified) -- Thu, 04/02/2009 - 08:39

Hi Robert,
I use the Pass aleph 3 with ARC LS17 to drive Quad 2905..sources Esoteric DV50 , Rega P3 , Dynavector DV20X
Cablings are mostly valhalla IC and speaker , with siltech gen 6 snowlake SATT between aleph3 and LS17 , power
conditioner THOR..
I am planning to upgrade my power , because although Aleph 3 is quite sufficient for moderate lestening level , in the end
the Aleph 3 just don't have enough power to drive the Quad , especially during complex passages..and also boomy bass etc..
My option is to choose either Pass XA 60.5 or ARC REF 110.. exactly the same price..Tough choices aren't they?
Please shed some light because in my country it's sometimes difficult to obtain samples for home auditioning.
I listen mostly to orchestral pieces and jazz music.
Thanks for the help..
 

mozvz (not verified) -- Thu, 04/02/2009 - 10:52

Gentlemen,
I have the XP-20 in my home for less then a week and doing a comparison to a CJ ACT 2 version 1. Both line stages are very good pieces, but I'm trying to decide on what flavor I prefer with limited time at the moment to compare. One of the items about the XP-20 that concerned me was Input 5 that is linked with the Home Theater (Unity Gain) function where it defaults to volume step 59 for unity gain. The XP-20 would maintain that 59 level unless you manually decrease the volume setting when switching inputs. Switching from Input 5 - HT (Unity Gain) to Input 3, the XP-20 maintained the same high volume and I forgot to change it to a lower level. When I switched to input 3, the results were dangerously loud as my component was in motion. In fairness to Pass, this is documented in their owners manual, but it's one of those items that could easily be forgotten.
 
I wrote Pass tech support about this situation and what I would consider a problem and they responded promptly and in a courteous manner. To get to the meat of the issue, they agreed that this is/was a  problem and had a chip fix that was available to current owners and were of course, putting into newly built units. The date I received the reply of the fix was around 3/31/09.  The chip replacement would decrease the volume level when switching from Input 5 - HT (Unity Gain) to any other input. I don't know if that level will be a fixed level or the previous sound level on that specific input would be saved and recalled. According to the mail, all that needed to be done was remove the cover, extract the old chip and replace it with the new one.
 

Robert Harley -- Fri, 04/03/2009 - 13:46

That's a tough call between the Reference 110 and the XA60.5. Can you listen to them before making a decision?
 
I'm also using the XP20, and find that quirk annoying as well. You just have to remember to reduce the gain when switching from input 5 to another input.

antono yuwono (not verified) -- Fri, 04/03/2009 - 14:04

The ARC dealer will let me home audition the REF 110 , but not so I'm afraid with the Pass , it's because the Pass is not well distributed in my country ( so they don't have stocks ) , unlike the ARC which I think is the market leader for Hi End components here..( so they HAVE stocks )..
So it is not possible to compare both at the same time , and I'm afraid in order to hear the XA60.5 I might have to buy it first..
Now my concern is reliability , as a solid state , I assume the Pass will need less maintenance and also more heavy duty than the REF 110..am I right? Or , are the current ARC products are also not easily broken?
Now in Your experiences , regarding neutrality , which one is more neutral? and what about the air/space/palpability? transparancy? and soundstaging?
Thank You Robert,
antono

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