Review: Pass Labs XA160.8 Amplifier

Category: Amplifiers

This is a short review to add to the observations already made by Sonicray in his excellent 7-17-14 review of the XA30.5 and XA30.8 amplifiers and by Peterayer’s 3-10-14 post in response to the thread started by Bo1972 on 2-25-14.

Both do an excellent job dissecting the differences they heard, and their descriptions are completely consistent with what I experienced. My objective here is simply to build on their comments by adding another perspective that may help others understand what is going on with these two designs.

For most of this year, like many others in the Audiogon community I had been wondering how the new Pass “Point 8” amplifiers compare to their Point 5 counterparts. After following the posts in the Audiogon forums, curiosity finally got the better of me and I called Mark Sammut at Reno Hi Fi to get the inside scoop.

Silly me. Long story short: as a result of several conversations I have just spent the last few weeks comparing a demo pair of Pass XA160.8 monoblocks to my current pair of XA160.5’s.

As a sidebar, I have to share in the overwhelming positive sentiment on Audiogon in support of Mark and Reno HiFi. Were it not for his business model that includes making a market in pre-owned Pass equipment, I would never have been able to leverage my way up over the past 10 years by way of used and demo units to my current level of gear.

As it turns out, this was one of the more interesting and challenging comparisons I’ve made as an audiophile. When I asked why Pass kept the .5 series in the product line after the .8’s were released the answer was that “…they will appeal to a segment of audiophiles.”

During my first listening session I learned why. Both amps are awe inspiring, but they present the music with different perspectives. In my system, the .5’s and the .8’s displayed distinctly different “WOW !” factors that I would distill to single words as follows:
XA 160.5: PRESENCE !!
XA 160.8: AIR !!

By “presence” I mean that the 160.5’s tended to push voices slightly forward, with lead or solo voices seemingly jumping out of the speakers into the room along the front plane of the panels. A good example is the track “Garfield’s Blackberry Blossom” on Lyle Lovett’s “Release Me” which begins with a series of beats on a kick drum to set the tempo. With the 160.5’s it sounds like I’m standing right in front of the drum kit with the compression waves hitting me right in the chest with each “thwack.” WOW!

By “air” I mean that the 160.8’s somehow create a sonic holodeck between my speakers that is more like hearing instruments in a natural space than being presented in a layered stereophonic soundfield. Again, WOW! But the immediate impact of those drumbeats was not as up close and personal as with the .5’s. The drum kit was just as loud and projected just as much bass energy but was placed in a perhaps more realistic position at the rear of the soundstage. Which is to say, not as “present.” I must admit that I kinda missed that bit of excitement.

After several days of warm-up, the first evening of listening was spent playing favorite tracks and switching back and forth between the amps. If I heard the .8’s first, the first impression when switching to the .5’s was: “Holy smokes, that solo voice (instrument) is RIGHT HERE !” If the sequence was reversed, the first impression was: “Holy smokes, these amps are even better than the 0.5’s, but why am I thinking that when the WOW factor of the .5’s is absent?”

The experience brought to mind a comment made by Anthony Cordesman in his review of the Pass Xs preamp and Xs 300 monoblocks in “The Absolute Sound” (May, 2014 issue):

“At a given point . . . describing the improvements in transparency and neutrality becomes an exercise similar to trying to write a long essay on different shades of red. You can try to make the prose exciting, but you really can’t describe the color red.”

If I were to describe the differences I heard using the standard audiophile lexicon, I would tell you that that both amps threw a soundstage that was wide and deep.Your speakers will “disappear” with either of these amps.

I would describe the 160.5’s as placing you more in the front row with the front of the soundstage seeming to be just slightly in front of the plane of the speakers instead of slightly behind it with the 160.8’s.

I would tell you that louder voices tend to be pushed forward with the 160.5’s making individual voices seem a bit larger than they ought to be. In contrast, they are more realistic in size but somewhat “laid back” with the 160.8’s.

On louder passages, the upper midrange and higher frequency voices (such as brass instruments and sibilants) sometimes take on more emphasis and a very slight glare with the 160.5’s, while the .8’s have smoother, but not-at-all rolled off highs. I didn’t come to the same conclusion as Sonicray in the review of the XA 30.8's (namely that there is some loss of detail with the 0.8 version), but found that the 160.8’s actually preserved the microdynamics of the signal better, albeit without the extra emphasis that adds to the perception of “presence.”

Finally, casting about for general adjectives, I’d tell you that the .5’s provide a bit more “excitement,” while the .8’s are more “natural.”

Of course, during my listening tests, I took care to match loudness levels. To dig deeper into what I was hearing, I measured the in-room frequency response with pink noise at 84 db and got the same results with both amps. That is to say, the differences I was hearing could not be explained by differences in frequency response, but that was no real surprise.

Finally, it occurred to me that I might be able to convey the differences I was hearing between these two amps in a more meaningful way if I could create a visual metaphor, so what follows is an attempt on my part to describe “red.”

Imagine you are drawing a picture of a stereo soundstage. You do this by drawing the image of each voice on a sheet of some transparent material, placing the image to the right, left or center on the sheet as it would appear on the stage, and then arranging the sheets front to back other to arrive at the composite image. Note that I am using the term “voice” to represent both human voices as well as individual instruments.

So, for example, to make a picture of a jazz ensemble, you might have drawings on separate transparent sheets of a tenor sax, a string bass, a piano, a drum kit and cymbals (one sheet for each), and a singer. You would arrive at the completed drawing of the soundstage by arranging the individual drawings in a layered fashion, perhaps with the drawings of the drums and cymbals at the rear, then in front of that would come the sheet with the drawing of the bass, then the piano, sax and finally the vocalist.

Now, to make this metaphor a bit more dynamic, imagine that you represent solo passages by moving the sheet with the drawing of that particular voice to the front position. Obviously, in a performance or recording, this is achieved by increasing the volume of the solo voice relative to the others.

In a perfect world, the sheets that carry the individual images of the voices would be perfectly transparent with no opacity, cloudiness, waviness or optical distortion. Thus, when you are looking through the layers, the images of the voices at the rear position are just as clear in focus and detail as the solo voice on the top.

Of course, perfection always eludes us, so now imagine that the sheets have a degree of translucency instead of being perfectly transparent. As a result, as you look through the sheets to whatever voice happens to be at the rear, you notice that it does not have the same clarity and focus as the solo image that is on the top. It is in its proper right-left / front -back position, and with a lot of space around it but it is blurred slightly so that the details of the drawing of the voice itself are not as apparent as they would be if this sheet happened to be in the front most position.

In the aggregate, because the sheets are not perfectly transparent, the overall effect is to make the solo (loudest) voice stand apart from the rest of the ensemble because it is less obscured. It is, in a word, more present.

Ultimately, this is what I heard with the .8’s. The voices at the back of the soundstage are just as detailed and nuanced as the loudest (solo) voices. When the piano is taking a solo, the subtlety of brushes on cymbals are just as apparent as during the drum solo. It’s not that the highs are being exaggerated - they are simply not being obscured. In the bottom octaves, there is just as much bass energy, but I hear more nuance and detail of the individual instruments and more of their interaction with the recording space (assuming that they were recorded in a real space) with the .8’s. There is slightly less of this detail with the 160.5’s, so I am hearing more of the pure pitch and timbre by default.

Borrowing from the visual metaphor once again, it’s as if the slight translucency of the sheets creates some sort of reference matrix that, while not obvious to the observer, binds the individual images into an overall representation of acoustic space, like the canvas support for an oil painting. When this is removed (or greatly reduced) the individual voices are rendered more as free-floating sources of sound. In retrospect, I think that I found the absence of this “matrix” to be somewhat disorienting at first. I can only speculate that this results from the lower noise floor of the .8’s.

Now the .5’s in no way sound “noisy” to me, and provide the quintessential “black” background from which sounds emerge, but Pass Labs claims to have reduced the noise floor of the .8 amps by 10db, which is a significant amount. Also, there are no capacitors in the signal path in the Point 8 designs, which may also explain the differences I heard between the amps with respect to the slight blurring of low level signals.

As I said earlier on, both the 160.5 and 160.8’s are unbelievable amps, and it’s clear to me that some will prefer one over the other depending on the type of music they prefer, what they listen for in their favorite music, the speakers, the room , and so on. I’m running all-Pass electronics (XP15, XP30, and XA160.5) with M-L Summit X speakers, and this setup along with my preferences favors the 160.8’s. Your results may vary, but I ended up trading in my 160.5’s.

Associated gear
Pass Labs XP 30
Pass Labs XP 15
Pass Labs XA 160.5
Martin-Logan Summit X