Pass Laboratories XA60.8 monoblock power amplifier Associated Equipment

Sidebar 2: Associated Equipment

Analog Sources: Thorens TD 124 turntable (reconditioned by Schopper AG); Ortofon RMG-212 (rebuilt), Thomas Schick 12" tonearms; Ortofon 90th Anniversary SPU cartridge.
Digital Sources: MacBook Pro computer (early 2015); Roon Optimized Core Kit running on Intel NUC computer with SSD drive; Benchmark DAC 1, Meridian Explorer2 USB, Mytek HiFi Brooklyn, PS Audio DirectStream DACs.
Preamplification: Auditorium 23 Standard step-up transformer, EAR 834P phono stage.
Power Amplifiers: Benchmark AHB-2 bridged for use as monoblocks), PS Audio BHK Signature 300 Mono monoblocks.
Integrated Amplifier: Leben Hi-Fi Stereo CS-600.
Loudspeakers: Alta Audio Titanium Hestia (review forthcoming), DeVore Fidelity The Nine.
Cables: USB: AudioQuest Carbon & Cinnamon & Coffee, Comprehensive Connectivity DXLRP-DXLRJ-6EXF. Interconnect: Auditorium 23, Chord (UK) Chorus & Chameleon Silver Plus, Mogami Gold, Sescom/Canare, Sescom/Mogami (XLR). Speaker: Auditorium 23. AC: Belden 14-gauge shielded, HOSA 14-gauge IEC, stock IEC.
Accessories: PS Audio PowerPlant P10 power conditioner, Oswalds Mill slate plinth (under turntable), Chilton's Durham media console in cherrywood, Auralex ProPanel Fabric-Wrapped Acoustical Absorption Panel (4' by 2' by 2", beveled).—Jim Austin

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

dalethorn's picture

The differences you describe confirm what I've experienced so many times, although I'm not privileged at this point to hear these monoblock beasties. Our ears, when normal, hear a dynamic range of nearly a trillion to one, a frequency range of 500-1000 to one, and numerous other effects like timing and phase differences. Despite not being a mathematician, I'd guess that the combination of these hearing properties are near-astronomical, which means that we have plenty of room for improvement in sound reproduction.

smargo's picture

"A youngish lady approached our table in G-string and pasties and did a tableside dance. My friend's jaw scraped the floor; I, noting her lack of enthusiasm, was unmoved. The stripper noted my impassivity and stated, with irony that at the time I somehow missed," "You're a hard man."

Isnt this too much information - really

mrkaic's picture

It isn’t.

es347's picture

..a hard man is good to find...apparently

amgradmd's picture

Just off the top of my head, the Decware model SE84UFO at 17 lbs and 4.6 total watts RMS (2.3 per channel) gives a weight/power ratio of 3.7, slightly higher than the ratio of the XA60.8.

tonykaz's picture

First the Surprise: PS Audio in the same breath as Pass! Those years ( 1980's ) that I was selling PS Audio stuff were years where Audio Research seemed to be the Top Gear Brand, PS Audio was "Entry" level.

Now-a-days, PS Audio's DACs, Pre-Amps, Amps & Power all stand with the Greats. No more looking down at PS, no more up-grading from PS. PS Audio has Arrived!!!

Yet again,

has there been any designer, who's work found it's way into more reviewer's personal music systems than N. Pass ? ( other than T.Edison )

I ( kind-of/sort-of ) tried to carry the Threshold Line ( back in the 1980s ) but already had the superb Electrocompaniet Line. I even had the Threshold National Sales Manager staying at my house for a short time but he couldn't/wouldn't let us have his stuff ( not even a try-out sample ). Sooooooo, I've never had my hands on any of these many Pass designs.

Now, today, it's too late for me. I have a rather pronounced leaning towards Active Loudspeakers with built-in Amps. Of course, Pass amps could be configured for an Active Loudspeaker System but it'd take some hefty convincing for me to consider it.

Tony in Michigan

ps. the little 30w. Pass Aleph SET Amp. still seems exciting

mrkaic's picture

The distortion at higher frequencies is unacceptably high. Also, Since when is 0.05% THD+N “extremely low” (see Fig. 7)? That is -66dBFS — average performance that you can get from many mass produced amplifiers.

johnnythunder's picture

over your comment that the THD is for this amp is "unacceptably high." JA didn't flag any measurements as being objectionable, flawed and able to heard (JA feel free to chime in here.) There is ZERO correlation between the sound quality of a mass market amplifier and this PASS amplifier even if the mass market amp has lower THD. Was your idol the late Julian Hirsch?

mrkaic's picture

So, is JA your god? He needs to flag something before you agree? Don’t you have your own views?

The Pass amp is mediocre and overpriced. And you could not tell it from a $300 TEAC class D in a blind test.

Finally, how much science and engineering have you studied? ANSWER WITHOUT EVASION!

ChrisS's picture



Shame on you, mrkaic!

mrkaic's picture

So unable to counter my devastatating scientific arguments. So angry as a consequence.

johnnythunder's picture

are what they do to your reputation here.

mrkaic's picture

Being disliked by subjectivists and/or anti science types is a badge of honor. I would hate to be liked by anti vaxxers, for example.

johnnythunder's picture

and you can continue to make your inane remarks in a forum where you are happily a rare, isolated minority opinion. The audio obectivists have long been on the verge of extinction anyway. Find a medium and have a nice laugh over cheap wine with Julian Hirsch.

mrkaic's picture

As far as I can see, subjectivists are very anti science. If they were not, they would admit several things.

1. The human ear is an imperfect instrument, not suited to analyze electronic components like modern amplifiers, DACs etc. You should admit that auditory illusions, placebo effects, and psychological factors play a major role in "hearing or listening to music". See this video and maybe you'll understand that what you "hear" is actually a product of your brain where the brain produces the "hearing" based on prior information and sensory inputs:

2. You would accept blind testing, no ifs, and or buts.

3. You would stop making unscientific claims about being able to hear the difference between different high resolution components, like modern DAC chips or amplifiers with distortion that is small enough to be below the threshold of hearing.

4. You would stop making unscientific claims about the effect of "audio grade" cables, fuses etc. on sound. There is none, unless the cables or fuses are damaged or really poorly made. Also, stop making unscientific claims about directionality of cables and fuses. It is stupid, flies in the face of science and engineering, as well as the practical experience of never noticing the directionality of wires while building an industrial and information society -- an effort that has required trillions of wires and connectors to be installed.

5. Stop claiming that audio memory is too short for blind testing. If it is too short for blind testing, it is too short for sighted testing as well.

6. There are other indications of anti-science stance by subjectivists, the above five should suffice for now.

ChrisS's picture

This is retail.

No one does blind testing.

No one does "science".

Josh Hill's picture

Last I checked, that was almost -5 dB SPL at 3 kHz:

The audibility or lack thereof of distortion in fact depends on psychoacoustic masking and weighting. The ear is extremely sensitive to some kinds of distortion, e.g., crossover notch distortion (which can be ABX'd, by the way), and very insensitive to e.g. low-order harmonic distortion.

Nelson Pass has studied the audibility of distortion extensively and has chosen to trade off offensive forms of distortion for benign ones. That's a wholly different level of expertise than is require to design an amplifier with low THD, a figure which has little to do with audible quality.

Anyone who isn't a tin ear can hear differences of this kind between amplifiers. But, of course, one must actually listen, something that few "objectivists" seem to have done.

You misunderstand completely the matter of audio memory, by the way. Audio is a complex, changing signal, and so poorly suited to ABX tests. The ear however will come to recognize the sound of a component with long-term listening. So while short-term switching does have a role to play, it is seldom the best way to hear subtle differences between amplifiers. One will eventually identify and start to hear and remember characteristics of the kind mentioned in the review -- is the bass wooly and uncontrolled, how much apparent depth is there, are the highs grainy and harsh or warm and smooth, etc.

Try it -- I can almost guarantee you'll be surprised.

mrkaic's picture

Read this:

ChrisS's picture

...scorned and ridiculed is the badge of a troll.

ChrisS's picture

Your posts have nothing to do with science.

Your baiting and trolling only inspire scorn and ridicule.

You have a devastated ego, mrkaic.

mrkaic's picture wanted to say a DEVASTATING ego. :))

ChrisS's picture

Only someone with a devastated ego baits and trolls.

ChrisS's picture your spelling!

johnnythunder's picture

he writes primarily about how MUSIC sounds to him on the components being reviewed. You never talk about MUSIC. You fixate on measurements and which immediately disqualifies your opinions on equipment to me (and to many many others here.)

My dad was in the record business. He was the district manager of a major music/hi-fi chain. i grew up living with good stereo equipment (Marantz etc.) I play bass guitar. I listen to music and go to classical concerts regularly. i know what an emotional connection to music is and i trust the writers of Stereophile to illuminate those things to me. I make my own decisions.

You troll and make inane remarks about THD. Argue with Paul McCartney about the high harmonic distortion in his bass guitar amp. Tell him that his VOX amp is overpriced and could be bettered by a mass market amp that can be bought for less at Guitar Center.

Allen Fant's picture

Excellent review- JA
I like your sense of humor and play on words- "stripper" and "hard man". She should have been more grateful ;)

Allen Fant's picture

2nd Note;
one could never own too many copies of Getz/Gilberto!

dumbo's picture

I noticed in the recently posted Golden Ear Triton video interview by the real JA that he was using what looked to be the XA60.8's. Perhaps the real JA will also offer his own 2cents on how the new XA60.8 sounds compared to XA60.5 he liked so much before?

Of course if he says the .8 is bad or worse I will disagree either way being a happily biased owner of this very Amp myself :)

Josh Hill's picture

Nelson Pass's remarks about the relative phase of second harmonic distortion and the perception of depth are one of the most interesting things I've read in a long time.

I've long wondered why some components, in particular tube amplifiers, exhibit more depth than others and have never found a satisfying explanations for this. I've long suspected that it was because the tubes were adding something -- the question being what.

Perhaps this, or a similar phenomenon, is the explanation?

gizmo101's picture

The battle btw objectivist and subjectivist will go on and never ends...
Nelson has scientific knowledge but if he pursues solely the scientific path, his amp will never sell. He knows this and therefore makes up something to appease those audio fools and be happy ever after...