REVIEW: Pass Labs XS 150, XA160.8, XA160.5

PeterA

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I have heard the Pass Labs XS150 amplifiers now in two different systems: Rockitman’s and MadFloyd’s. Christian’s system, room, and most of his music were unfamiliar to me so I could barely begin to understand what these amps contributed to the overall sound. I enjoyed hearing the system, but all I could really conclude was that the amps did a good job driving and controlling his Wilson speakers. However, I know Ian’s system and room quite well, having enjoyed its evolution for the past four years.

Last weekend, fellow member Al M. and I heard Ian’s system again. Ian has both the Pass XA 160.8s and the XS 150s. We compared the two amplifiers directly. To fully appreciate what an accomplishment the XS 150 is, I think it helps to understand how past designs have sounded and how the sound of Pass amps is evolving.

I am a big fan of Pass Labs products and have owned the Aleph 3, Aleph 5, Aleph 2, XA 160, XA100.5, and XA160.5 amplifiers, the Aleph P, X-1, and XP-20 pre amplifiers, and the Ono, XOno, and XP-25 phono amplifiers.

To better understand the XS150, I would like to first describe how the XA160.5 and XA160.8 sound. I directly compared these two amps at Ian’s house and then later at my house.

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In Ian’s system: Driving the Magico S5 speakers, the 160.5 sounded smooth, warm, and full bodied. The tone was beautiful, and it was a pleasant non fatiguing sound. The 160.8, by contrast, was more resolving, more controlled, and more dynamic, but it lacked a bit of soul or beauty. It was slightly sterile sounding. In this system, there was a clear difference.
Both amplifiers sounded good for different reasons, but they each had some weaknesses, so, there were trade offs. In this system, I preferred the XA160.8 slightly overall because of the better control and resolution.

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In my system: Driving the Magico Mini II speakers, the 160.5 sounded very much like they did at Ian’s house. The sound was smooth, beautiful and non fatiguing, but the amps also had the clarity, drive and control of the 160.8s. Dynamics were great. Perhaps because of the smaller room and smaller, less extended speakers, the 160.5 sounded more complete than they did in Ian’s system. The overall sound was, and is, very natural and convincing. The only advantage the .8s had in my system was slightly better resolution and an ability to better separate the instruments in the most complex music. However, the .8s lacked the tonal beauty and richness of the .5s and did not provide quite the emotional connection to the music that is so critical for me, so I preferred the XA160.5s in my system.

This leads us to XS150. Since the .5 and .8 comparison, Ian replaced the S5s with the Magico M Project speakers. I had heard these new speakers with the XA 160.8 three times before this most recent audition. Ian, Al M. and I began by listening to the XA160.8. The system sounded great. There was good resolution, nice tone, dynamics and presence. It sounded very much like I remember it sounding the last time I heard it, with the major exception of better presence, but that was a result of Ian finding a better speaker location for the M Pros.

We then switched over to the XS150 and listened to the same two tracks that we had just heard with the XA160.8. The sound seemed different and yet familiar at the same time. It had all of the control, resolution and clarity that we heard with the 160.8, but it suddenly also had the rich and warm tone, and overall beauty that I remember hearing with the 160.5 and S5 speakers.

The striking thing is that the XS150 seems to combine the best of these other two amplifiers. It is a little difficult to describe exactly what is going on, but I think that the .8 sounds so clean, vivid and detailed because it resolves a note’s fundamental frequency better than it does its harmonics. The emphasis is on the leading edge and the fundamental. The harmonics are less pronounced and resolved. The sound is less complex and I think this is why it sounds cleaner, crisper and more detailed.

The XA160.5, by contrast, better resolves the note’s harmonics. I think that is why this amp sounds so rich, warm and beautiful.

The greatness of the XS150 is that it resolves the entire note, the fundamental and its harmonics. The transient, sustain and decay are reproduced equally. The sound is more complete. There is an overlap to the sound as old notes decay and new notes begin. Music’s complexity is reproduced in full and the result is an incredible sense of flow and continuousness. The XS has all of the control, speed and resolution of the .8 and all of the richness, warmth and beauty of the .5. It combines the strengths of each amp and has none of their weaknesses.

The XS150 is the highest resolving and most natural sounding amplifier that I have ever heard. It represents the evolution of Pass designs and seems to be the culmination of all of their past best efforts. It is a real achievement.
 
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Alpinist

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Terrific review, Peter! I owned both the XA-100.5 and the XA-100.8. You hit the nail right on the head. I definitely agree about the harmonics.

Best,
Ken
 

Robert

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Hi Peter,

I'm trying to read between the lines and press you a little about a value analysis. If cost is no concern and everything else is totally optimized, sure on the XS150. Do you think the 160.5 remains the one to beat for the price? There is a vast differential in cost.
 

PeterA

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Hi Peter,

I'm trying to read between the lines and press you a little about a value analysis. If cost is no concern and everything else is totally optimized, sure on the XS150. Do you think the 160.5 remains the one to beat for the price? There is a vast differential in cost.

That is an interesting question, Robert, and no so easy to answer. In my system, the .5 can drive and control my speakers, so it is really a question of taste between the .8 and .5 and which sound one prefers. I prefer the .5, even if it were priced the same as the .8. I thought about trading for the .8, but after hearing it again, decided that I like the .5 better, regardless of price. Now, I once owned the XA100.5 and that could not quite drive my speakers, so in that case, the XA100.8 might be better, though I have not heard it in my system.

In Ian's system, the XA160.5 could not drive his new Magico M Pro speakers and the sound was overly soft. It was still beautiful, but on large scale classical, it did not have the necessary clarity and resolution. Dynamics and bass suffered, so the XA160.8 was the better choice, even for the additional $10K.

I happen to think that Pass had too many options available after the introduction of the .8. With the X and XA lines, and .5 and .8, there was just too much product. I also suspect that the .5 faceplate was too expensive and they needed to drop the oldest design. But that means that in the right system and room, some of the .5 amps represent great value now on the used market. They are great looking, combine the sweetness of the old Aleph series plus lower distortion and better control than the old XA. The do not have quite the power of the X series or the resolution of the new .8 but it is system and taste dependent, and they may be the perfect option in the right system.

I plan to keep my 160.5 until if and when I can buy the XS.
 

KeithR

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Peter- I understand you're agreement with Pass over the years, but it would be nice to hear how you distinguish them vs other popular SS amps?

I'm not surprised the 160s were short of power- as I surmised on another thread a few months ago. I'm glad the XS150s with separate power supplies appear to do better in this regard with the big Magicos.
 

PeterA

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Peter- I understand you're agreement with Pass over the years, but it would be nice to hear how you distinguish them vs other popular SS amps?

I'm not surprised the 160s were short of power- as I surmised on another thread a few months ago. I'm glad the XS150s with separate power supplies appear to do better in this regard with the big Magicos.

To clarify the power issue: The XA160.5 had slightly less control of the M Project than did the XA160.8. The XA 160.8 and XS 150 both seemed to control the M Project with equal ability. The XS simply has some of the strengths of the .5 that are missing in the .8. The XS combines the strengths of both amps, IMO.

I have not had other brands in my own system since I bought my first Pass, the Aleph 3. I like the Pass amps but I have no agreement with the company.

I have heard various Pass amps as well as amps by D'Agostino, Ayre, Lamm and Doshi in MadFloyd's system. These were heard driving his various Wilson speakers, the Sophia, Sasha and Alexia. I preferred his Pass amps with the Wilsons. He then switched to the Magico S5 and settled on Pass Labs. Perhaps you can contact MadFloyd directly or look up some of the history in his system thread.
 

Howard

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Mar 22, 2014
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Out of curiosity Peter - was the comparison between the XA160.5s and XA160.8s driving the M-Pros in Ian's system done before or after the electrical issues that were limiting current to the amps were worked out?
 

PeterA

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Out of curiosity Peter - was the comparison between the XA160.5s and XA160.8s driving the M-Pros in Ian's system done before or after the electrical issues that were limiting current to the amps were worked out?

Good question Howard. I can't remember. Perhaps you can PM Ian. The .8/XS comparison that I heard with the M Pros was after he sorted out the electrical issues, but I can't remember if the .5/.8 was done before or after.
 

Robert < NxLT > Slowinski

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Hi Peter,

Thanks for this. Now you know what I was going through with my 60.8 vs Aleph X. :)
Now I'm make other approach with my point 8 amps.
I have ordered Aqua la Scala MK 2 DAC with tubes in it. I hope to gain with it best thing of the two worlds. If yes I upgrade to bigger 100.8. Otherwise I go for the 160.5 and wil be happy for many years.
 

Alpinist

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Hi Peter,

Thanks for this. Now you know what I was going through with my 60.8 vs Aleph X. :)
Now I'm make other approach with my point 8 amps.
I have ordered Aqua la Scala MK 2 DAC with tubes in it. I hope to gain with it best thing of the two worlds. If yes I upgrade to bigger 100.8. Otherwise I go for the 160.5 and wil be happy for many years.

I loved the sound of my K-01/XP-30/XA-100.5/Salon 2 system. Warm, organic and gorgeous sounding. I moved to the XA-100.8 and initially thought it was a major upgrade due to the improved clarity and transparency. But after a time, I realized the magic that I had with the XA-100.5 was long gone. I ended up selling the XA-100.8. Moral of this story, go for the XA-160.5. Just my opinion.

Best,
Ken
 
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Robert

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Good information.
 

PeterA

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Thanks Ken for the advice. I asked my dealer if it is possible to get the "discontinued" XA 160.5 Amp`s.
Are you back to XA 100.5 ?

There are two XA160.5s for sale at good prices on Audiogon right now. I think whether you prefer the .5 or the .8 will have a lot to do with the frequency range of your speakers and how difficult your speakers are to drive as well as the size of your room and volume level you prefer.

My speakers do not go very low and I have a small room and listen mostly to acoustic music not very loud. So in my case, the .5 is adequate. For larger scale, louder volume and greater low frequency extension with complex full orchestral music or loud rock, the .8 might be preferred.
 

Alpinist

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Thanks Ken for the advice. I asked my dealer if it is possible to get the "discontinued" XA 160.5 Amp`s.
Are you back to XA 100.5 ?

Reno Hi Fi still has new and demo XA-160.5. Their demo amps are basically new open box amps with a full warranty but at a much lower price. Reno Hi Fi also offers a 10-day in home demo period. If after 10 days, you want to return them, you just have to pay for return shipping.

After I sold my XA-100.8 I ended up totally rolling my system. I am currently running Esoteric K-01X, Soulution 520 preamp, Soulution 501 mono amps and Raidho D3 V2 speakers. I am extremely happy with my new system.

Best,
Ken
 

Bruce B

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I'm glad to have my .5 amps. My next upgrade will be the XS series. Never really connected with the .8 series.
 

Ron Resnick

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Thank you, Peter, for that interesting and informative review! As far as you can determine are the 160.5 and the XS identical on the warmth/richness/beauty spectrum?
 

PeterA

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Thank you, Peter, for that interesting and informative review! As far as you can determine are the 160.5 and the XS identical on the warmth/richness/beauty spectrum?

Thanks Ron. I can not answer that as I have not directly compared the .5 and XS amplifiers directly in the same system. But having directly compared the .5 to the .8 in two systems and then directly compared the .8 to the XS in one system, I am confident about my observation that the XS presents a more complete picture of the musical note as well as having lots of clean power and low noise.

The XA160.5 presents a warm, rich and beautiful sound. The .8 has more control, dynamics and resolution. The XS combines the best qualities of both.
 

Robert < NxLT > Slowinski

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Thanks Peter and Ken for the buying advice, but I’m living in Europe and here is more difficult to get the 160.5 amps.
I contacted my dealer and he is going to give me some good price ( I hoop ) for the 160.5 and I can return the XA 60.8 if I want to.
I will be doing this after I receive my DAC Aqua la Scala MK2 and test it with my XA 60.8
If I like the sound then I upgrade to 100.8 otherwise I go for the XA 160.5
 

Ron Resnick

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Thank you, Peter. A friend of mine is happily using .8s in a passive bi-amped configuration to drive the cones in his Neoliths.

Is the .8 the warmest and harmonically richest solid state amplifier you have ever auditioned?
 

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