What are the weak points of Pass amps and pre-amps ?


Though there are perhaps better transistor amps, but Pass seems to be an excellent choice for many.
What is your experience with them, if you could elaborate ? Integrateds as well.
inna
Perhaps I have the wrong model but I thought the Coda Continuum 8 amplifier is a high biased A/AB amplifier not 150 watts pure class A. With regard to whether the X series or XA series is "better," I assumed the XA would be preferred but when I talked to Kent at Pass Labs he steered me toward the X series for my speakers (Thiels)...he said the X series would be a better match. So I was prepared to spend significantly more money but I ended up with a X150.8 and its one of the most harmonically rich and detailed amplifiers I’ve ever heard. So much so I was thinking about trying one of their preamps.
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the new XP-22 has an off switch, not familiar with the new phono stages, and the amps have always had a standby and a separate off switch...
benjie, I see. As I understood so far, only slight negatives can be less than perfect precision, speed, dynamics and resolution. Overall, Pass seems to be an excellent choice for many people. Size can be a problem in smaller rooms but look at some other amps out there.
You can’t spell “Tru-Fi” without “fruit.”  Coincidence?  I think not.

Obligatory relevant thread comment: Pass makes some really good stuff.  
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Do you think it is possible for some of you to take it outside of my thread ?  Please give it a try.
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Mitch2,
I recently owned the GamuT 250i mono’s. Got them from Kyomi Audio. Awesome guy. I ended up trading them to Scott Walker for my Speakers. Really nice amps. I owned the Clayton 30 and 100 before. I really liked the Clayton’s a lot at the time a few years back. 

The GamuT’s only use a pair of big old welder type of output devices per channel. Kind of a cool approach. I found the GamuT to be much better amps then the Clayton’s but they should be as they cost way more. The Clayton’s were slower, more plodding but still had decent PRAT and bit more set back and laid back, warmer with a bit thicker in comparison. Still they were very nice but the GamuT was a very different animal. GamuT has a more modern, transparent, more resolute approach. 

I actually prefer my currant Pass amps the 160.8 to the GamuT. Fuller, bigger, lusher, not as quick but I’m a sucker for the Pass Class A sound. Always have been so I’m sort of biased. 
Hi heat - low driver control - not as dynamic at lower volumes as others - transparent but there are more transparent - but so well rounded and as a whole they are great but I do wish they grabbed ahold of the drivers a little better but that’s part of the give and take with the lush sound so it is what it is but still would like better control. I’ve owned Aleph 3, 5, J, 30, F2, F2J, J2, 150.5, 350.5, 250.8, 160.8 and prob few others I forget. They were all great. Best sounding - no doubt there - the F2J is best sounding - you just need the correct speaker for it but it’s so pure and perfect. If he could ever get that sound into 100watts he could charge what he wanted for it. 
Go Bo Go. Nobody here know trufi like Bo. You are all inferior mortals with little mouse ears... admit it.
The first Pass Labs I bought were the XA-100.5 with an XP-20 in 2009. But later I preferred the X-series. I find out that using the right source and cables it has more advantages compared to the XA-series.

It has a little more space and details in the high frequencies. And I also prefer more control in the low frequencies with the X-series. When I bought Purist Audio Limited Edition power cables I became the same level in layering as the XA-series. But with more details and control.

At the end, I will go for the XS series. The extra current will be enough!
I love Pass and used different mono amps and power amps of them in the last 8 years of time. I choose products based on their DNA. I think they created stunning amps and very good preamps. But I prefer their amps.

When you work by Tru-Fi you want to use all the aspects/properties of sound at the max. The 3-dimensional sound stage is an aspect/property of sound. I have compared many amps also regarding this part. We create a huge holographic stage thanks to the stage DNA of Pass Labs.

Pass Labs is also able to create a very deep, wide and high stage. Diversity in height we call a High-End ++ property. When an audio system can reveal the differences in height of both voices and instruments the harmonics change of a recording.

When we use amps who are not able to reveal diversity in height we always hear a much lower level in the layering of the sound. The limitation Pass Labs power amps and preamps both own is a limited level in the individual focus of instruments and voices. I had many conversations about this with Desmond Harrington (President of Pass Labs) and he was aware of this.

You can adapt it with cables and a source as well. But when we use preamps who own a superior level in intimate focus it becomes clear that it has a huge advantage. It creates a much more lifelike palpable image of voices and instruments.

That is why I want to do presentations with Conservatorium students at audio shows. To let people experience what intimate focus of voices and instruments is and does. After that, I will give a demo with a Tru-Fi system. So they will understand that it is just like in reality.
Owned Spectral electronics for 20 years. Hyper detailed, bright, finicky about setup, the latest SV30 pre amp did not want to play well with my Manley Steelhead or Pass XOno phonostages, DMA 360 amps had a large "thump" at turn on.

Switched to Pass in 2016, Extremely happy with Pass.

Pair of XA160.8s and XP20 linestage.

Dead Quiet. No thumps, buzzes, hums, plays well with others.

All the detail that the Spectral had, but smoother, a little warmer sound, Bass is better, deeper, more textured. Mid range is closer to Live. Highs are not bright and harsh. Can enjoy for long listening sessions.

Yes, they do run warm, but not a problem at my place. At my dealer, in his large, but closed room, it gets stuffy. At 140 lbs. each, they are staying where they are.

Better equipment out there? Of course, to each individuals preferences. Pick what you like. For me, the Pass gear is a bargain and hassle free. Do not see myself looking for better gear. I am off the merry-go- round.


I remember running a Yamaha 1970s CA 1000 integrated amp with 15 watts Class A switch.  It got rather warm but it did sound superior to the Class A/B 70 watts (about).  The 15 watts sounded more musically involving, smoother and quieter than Class A/B.  

I own an EAR 890 which is 70 watts Class A.  It gets burning hot on the chassis and transformers after 30 minutes. 

I now use a pair of monoblock 130 watt tube amps running Class A/B.  It is a voltage regulated design which runs so cool that after 2 hours, you can place your hand on the transformers which are merely warm.  Plus the sound is superior to the EAR 890.  

I don't think there is an advantage running Class A over Class A/B, depending on design.  The cost of powering Class A and the heat are definitely a consideration.
I have owned a number of Pass Amps and pre-amps, as well as several First Watt Amps.

Right now I have a xa30.8, and x20 pre and x10 phono.

Every Pass amp and pre amp I've owned has sounded a bit different, but they've all sounded excellent.

The people at Pass are great to deal with, as is Mark from Reno Hi-Fi ( where I've purchased all my Pass equipment).

I suppose there is better equipment, but I would say that if you are not satisfied with the sound of Pass then you will likely not be satisfied with anything.

Of course this is just one man's opinion, but I think it's a valid one.

@jetter 

Gotcha, really looks like a whole lot of useless space and words to me.  No idea what it has to do with Pass Labs...
cowan217, agree about all the great pass reviews.  But a lot of us call whatever we have as the best thing ever.  Then out next purchase is the new best thing better than what we had before.  Its good to know if there is something not perfect about an item to see if that "thing" is a deal breaker or not of consequence to us personally. 

I have never heard a pass, but I think that other than the heat I would love to have one.  
dep14, Bo does not have one purchase or sale on A'gon.  At first I use to read his posts years ago, then stopped completely and won't again.  But as far as I know he has never tried to sell anything and I don't think you could hire him to install a system.  But he kills threads with pages and pages and pages of posts all saying the same thing.
Man... at least Troy is selling legitimate brands and equipment. 

Bo, appears to be using the "show-up and throw-up" method of selling... garbage.
Was the initial post designed to just generate a platform on which to try to dig up criticism of Pass product?

The product is consistently reviewed as being some of the best our there - up against any other product. 
@bo1972 Unless you have something to say about your experiences listening to Pass Labs amps, please leave the thread and start your own to talk about your product. Otherwise, I suggest everyone else report the posts. 
Rabbit hole! Whack a mole! Isn't there a whack a mole fan around here? Please direct teleportation tractor beam at @bo1972. Cheers,
Spencer
Sound will always be about what you can hear. Each human being prefers any audio system that can reveal all the details and layers of the music over any incomplete created trial&error system.

Based on that fact that thinking audio is a matter of personal taste is the biggest scam ever told and believed. Audio=sound= all aspects/properties of sound= the truth.

No human being prefers an incomplete audio system. Our emotion works the same way and again we are talking about a 100% fact. We have our personal preferences regarding music and artists. But.....music will always contain different aspects and you need them all.

Ask any audio lover about what sound is and which aspects/properties it owns? And they often have no F.idea. This is walking on a very thin line and never be able to understand why your sound and stage is what you can hear. So your trial&error system is being created without understanding anything about music and sound. You just gamble and hope it will become alright. When you would use your brain and common sense it is very easy to become aware that you do not know what you are doing.

This is not what you would like to hear maybe. But audio is all about sound and the truth. And has nothing to do with doing audio by trail&error what is doing audio without a real foundation. All manufacturers who work in audio for a long time just like me all agreed. Because we are talking about facts. The sound will always tell the truth. No incomplete audio system will ever be able to experience the emotion of the music.

Ask people how human emotion works and how it relates to music. They all don’t F. know. How for God sake you could think and even believe that you can create a stunning and ultimate audio system without any real foundation by audio-gambling. Trial&error is 100% audio-gambling and again we are talking about a 100% fact. And yes the truth is hard, but you need to accept it to reach that stunning and ultimate level in sound.

Trial&error is the main reason why so many people all over the world are not happy with their system. When you would understand what sound is and what it does it will become clear and even easy to understand why your system lacks emotion. The audio market is decreasing every single year. Ask people why they are not that interested in audio any more..............

They will say that what they heard did not convince them and it did not do a lot with their emotion. Incomplete audio created trial&error systems will always limit people. Based on the fact that you need all the aspects of sound to experience the emotion of your beloved music. Just start to read about music and our human emotion and maybe one day you will understand.

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Interesting comments in this thread.   I own big Class A amps and really like much about the sound but there can also be advantages to how Class AB amps present certain types of music.  Another thing I have found to matter is whether the output stage is driven by MOSFETs or bipolar transistors, with the MOSFETs usually IME offering a somewhat softer sound that is sometimes described as tube-like.  PASS and BAT use MOSFETs.  I tend to like amps with a bipolar output stage (like my Claytons), although I would like to hear the GamuT 250i monos and Pass' 260.8s both of which use MOSFETs.
I have heard good things about the sound of CODA amplifiers (bipolar output stage) but have been a bit confused as to why they have so many offerings.  IMO they would do better to establish a more concise line-up and stick with it - and offer more monoblock options.  The cosmetics seem a bit dated also but of course that is personal preference.
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@jetter 

Yeah... I under estimated the volume again.  Definitely hitting peaks over 100db+

Oh, on the subject of Pass Labs no question they underestimate power and the class A bias.  Bias meter barely moving.

87db 6ohm nominal load on the 5000's.  Don't HAVE to have big power, but man they respond.
@dgarretson

I was just making sure I could smell what the Rock...was... cookin!

I will say however, right now my wife and kids are not home, I am in my audio room with my 250.8, XP12, and my Ohm Walsh 5000’s and getting my dose of Metal and Classical all at once. Metallica S&M.

Feeling pretty emotional listening to Metallica and the SFSO rock One, just knowing Sandman comes next and closing with Battery.

Of course, that could be the emotion of pure Joy,  90+ db’s and no one to tell me to turn it down.

Tru-Fi stands for True Fidelity. You want to hear all your music as it sounds during the recording. Sound contains different aspects/properties. All different aspects of sound can even influence human emotion.

When you would read about how our emotion works regarding music you will find out that there are 3 aspects that influence our emotion during listening to music. We do a lot of research in sound all the time. As we use many modifications on amps, preamps, sources, power supplies and subwoofers. 

When you judge most audio products on the aspects/properties they can reveal it becomes very easy to understand what is missing and what can be heard. Most people do not understand why their system does not give them the emotional feeling they are looking for.

When you would know more about sound and how the human emotion works it becomes clear why most systems lack emotion. Diversity (lagering) in sound is the most important aspect of sound. Due to the fact that this part can create the biggest influence on our emotion during listening to your beloved music.

But when you would judge most digital sources and even amps these days on this part, the facts (the sound you can perceive) prove how limited the layering in sound is. When a system can only create a low or limited level in diversity in sound all human beings will not feel a lot of emotion during listening to their music.

When we let new clients hear their own beloved music with a Tru-Fi system, they feel and understand the huge difference in emotion. We use different songs to teach people what layering in sound is. And what it does to their emotion.

We use many different songs to explain the aspects which they miss in their system. We want all audio systems we create and adapt to be able to reveal all the aspects of sound. And what it does to all people is always the same. They use their system so much more frequently and longer at the same time ever before.

Tru-Fi proves on facts that it outperforms any created system by trial&error. It also proves that you need all the aspects of sound to be connected to the music. And experience the emotion the music possesses.
@bo1972 

I've never heard of Tru-Fi, is this a company, something you sell/rep work for?  Just never heard of it.
THE meter is useless and you're paying for it anyway. The speaker "wing" connectors on Pass and many other top brands can make it difficult to connect heavy speaker wire with spade lugs. If you don't get the XS series with outboard power supplies you're not getting everything the company has been able to achieve. Any preamp or integrated amp without at least ONE tape loop (IOW a fixed-level output jack) is off my list of versatility. Also one must consider whether or not you can listen to headphones or not, even with an external headphone amp. As for X or XA, it's certainly a conundrum that makes you choose one or the other, and if you're not happy after 3 months or ? months with the sound, you're going to give yourself an "ulcer" thinking you made the wrong choice, making the hobby even MORE complicated than it is already.
My dad had a Blaupunkt TUBE radio many years ago that sounded so sweet and smooth
in spite of its limited power, etc. that a lot of people here may not have ever experienced. So it pays to understand just what solid-state is up against if you want to evaluate what's possible. Having said all that, Pass is a good fit for most audio "fanatics" and should satisfy most of us that can afford something they make. Not all speakers are a good fit for a Pass amp , but that would not be an excessively long list. My main beef with ANY product is limited connectivity, whether it's a reel-to-reel or wire, headphones, a subwoofer, whatever you need it to do.
Lastly, some components looked good 20 years ago and they still look great today (ex. a Lin turntable). Facel-lifts, meters, gadgets, are extraneous (ex.Krell) and the cost is passed on to the customer. The "old" yellow-and-black Rolls that Arther had looked better than the ones they're making now. Just making a point. 
Inna, I have a Pass Labs XA30.8 amp and a Pass Labs XP-20 preamp. They are great. The amp is a bit heavy 100 lbs, being class A it puts out a little heat. I don’t run my amp 24/7. 1 hr warmup is all that’s required for excellent sonics. I have no negatives for the Pass Labs XP-20. As with all equipment I would say ~ 500 hrs breakin to hear the “real deal”
I have done thousands of tests in audio in over 20 years of time. I also compared many amps with each other. In stage depth, width and height the differences are huge.

A friend of mine had a concert room with a Steinway wing. I loved the intimate presentation of both voices and instruments during these concerts. It has become an important part of our Tru-Fi. Acoustic recordings need to give the same feeling.

With our Statement Audio Pro-measurement, we can come so much closer to the live experiences I had. It limits the influences of the room and gives access to a superior level in detail and layers of each recording.

Each part in any system owns it’s DNA. I did spend thousands of hours and tests in over 20 years of time to be able to reveal the full DNA of each individual part of an audio system. I have been working in audio full time over 20 years of time now.

Working by Tru-Fi you can create a superior level in realism and emotion compared to any trial&error created system. When we let new clients hear a Tru-Fi system, they understand often after a few sounds how limited their own system is.

The differences are created by the superior level in emotion. Emotion is the only key and way to success in audio. That is why an audio system needs to reveal all the details and layers of the recording. We always ask new clients to bring in their own music they know best.

Then it is very easy to feel and hear that Tru-Fi overrules their incomplete and limited trial&error system. The biggest problem in audio is that almost all brands and products cannot reveal all the aspects of sound. This means that these products will always create a lower level of emotion.

Only those systems who are able to reveal all the details and layers of a recording can create an emotional and addictive sound. Most people own incomplete audio systems with acoustic limitations. This will often keep them from buying new music each week.

In over 20 years of time, I visited hundreds of people with serious systems. I was often surprised by how little music they have. Trial&error will never make them understand what they change in their system. They focus a lot more on the sound and stage of their system. Trial&error will often limit people from listening to their music. The fact that they often have little music proves it.






@bo1972 

So here is the thing.  Even when talking about the "realism" of instruments.  

I would make the argument that anything amplified - ultimately doesn't have much "3d" sound.  Electric Guitar/Bass in particular.   Anytime you are at a concert which is amplified, regardless of genre it doesn't matter.  It's being pushed through amps firing in one direction, fed to a PA system.

Now, a small venue, piano, acoustic instruments, horns, etc.. Unamplified music, a singer in a small venue etc.  I can buy some 3d realism to that.  But, the soundwaves are still subject to the space they are in.  But take out the amp/PA system I do think there is some 3d realism to acoustic instuments.

An amp - really just sends along the signal recorded.  Now do some amps add some bloom - sure, but it's just sending along the signal it receives. I will grant that very, very few amps truly are neutral.

But for 3d realism, I would argue that the source (recording and whatever is passing that along), along with the speakers and the room they are in that make the biggest difference in any 3d illusion given. Obviously, the pre-amp and amp CAN flavor that, but really what you are looking for is a tremendous source, a pre and amp that impart nothing, and killer speakers and a killer room.

Now, a killer recording can help you imagine where the individual players are in a given recording.  We all find that cool.

So, not sure if this has much to do with Pass strengths or weaknesses.  Just decided to start typing some thoughts on this... I'm on record liking my Pass Amp and do not think it's dead neutral.  I do however really like it.






I have owned different Pass power amps and mono amps. I had contact with Desmond Harrington (President of Pass Labs) for a long time. I also owned the XP-20. It is a good preamp, but not a stunning one.

When you judge Pass Labs on all the aspects/properties of sound. It will become clear that they lack realism in the individual focus of voices and instruments. When you listen to voices and instruments in real they are very small and direct. The Pass Labs preamp and power amp are not able to create the intimate focus as in real.

Desmond told me that the 0.8 series make voices and instruments smaller and more palpable. But it is still not among the best. In my world, it is only about the best possible. The rest is 100% useless in my world.

Voices and instruments are not only very small and direct. In real you can even hear the shape of a voice and instrument. I call it a High End ++ property. When you judge Pass Labs on this, it shows that it cannot reveal this part.

When I was in Munich at the High-End show in 2015, only one system of over 700.000 euro who was able to reveal a 3D shape of voices and instruments. The problem in audio is that most people who work in this world or see it as their hobby know very little about sound and music. Even most manufacturers have very limited knowledge and insight in sound in general.

When I talk with them about the acoustics, electro-smog, high-frequency noise and magnetism they still know very little. It becomes clear why so many audio brands and products are still sound so different than music sounds in real.

You need to understand all the aspects that influence both sound and stage. Sound is very complex and can only be understood and guided when you understand the influence of all these aspects. In all other situations, you still do audio by trial&error. This will always be audio without any real foundation. It can only create audio systems that miss essential parts of sound with also many flaws.


I do not know Troy and have never shopped in his store. I enjoy his posts. While he certainly has some motive to promote the brands he sells, his thorough and knowledgeable insights allow me to learn about large, heavy and expensive gear w/o having to buy (and sell) everything out there. I purchase from (the few remaining) brick and mortar stores locally as well as from retailers and private sellers on A-Gon. I do not post very often these days, but do read many of the A-Gon threads. At 61, & with a bad heart, my audio addiction has become more difficult to feed. I no longer find it at all easy to transport, unbox, set-up, re-box and ship large and heavy equipment. Thanks to Troy and others who post and provide insight to the fine Audio gear that is becoming more and more difficult to hear in stores and audition at home.


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A few years ago I bought a pre-owned Pass INT-150.   I replaced a Wyred4sound 4 channel amplifier, because I no longer needed to bi-amp.  Talk about going from apples to oranges... The Pass was kind of an impulse buy.  I did not compare to anything else at the time.  I can't really come up with any weak points other than that yes, they do run very warm.  That is intentional though.  I don't plan on changing unless some other system change forces me to.  I can envision a scenario where an integrated would not be appropriate, but for my system now, I prefer the convenience and the sound synergy of the Pass integrated.
pistha, while you were talking with Pass Labs did you ask them their opinion regarding the XA25 driving your Sophias? I ask because I believe my speakers also dip rather low although I only know their nominal impedence.
@medwardo - I have the X250.5 driving my sophia 3s and have the itch to move to an all class A. Even though the X250.5 offers the first 25W in class A. I spoke with Pass and they didnt think highly of a move from the 250.5 to the XA30/60.5. They did mention that a move to XA100.5 will be very rewarding and worth the move. Is your XA25 able to drive the Sophias well? They are known to dip well below 2 ohms at low frequencies.
I have not heard all of Pass Labs amps, but from recollection of a few I did owned it’s good but not great.
I had the X350, X350.5, XA100.5, XA160.5, XA160.8, compares to MSB M202, M203, Lamm M2.2 and ARC REF250 and even Bryston 28B3, one would wonders what the hypes was all about.
As you can see, I did fall for the hypes with owning 5 different Pass models.
Not bashing on Pass, I’m sure the XS is a must for class A enthusiast, including myself.

 If you are worried about the price of Pass amps and happen to have efficient speakers, try the First Watt line. Wonderful amps that won't break your bank.