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Pass Labs 20 Years and Counting

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Old 12-09-2012, 01:38 AM
mbovaird mbovaird is offline
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Default My New Pass Amps - The Review and Faceoff

Background

Yesterday, I set out to compare my new Pass xa160.5’s vs my McIntosh 2301’s vs my Classe CA-2300 amps. Each amp or set of amps (the 2301’s and 160.5’s are monoblocks) represents a different approach, a different topology if you will, to delivering sound, and ultimately, making music. This included, Tube, Class A and Class AB. Obviously Class-D or any kind of Digital Hybrid was not part of this evaluation.

For the review, I selected 2 hours of music which utilized 90 minutes of a wide variety of music from my music server including ripped Red Book CD’s, High Res (24/192 and 24/96) and DSD files. For the final 30 minutes, I used standard red book CD’s and SACD’s. I would have liked to included Vinyl in my review, but I was unable to due the fact that I am still awaiting my new phonostage (Zesto PS1)

My music list contained a wide variety of music ranging from jazz to classical to pop to rock to acoustic and solo performances. As I find myself listening to a wide variety of music, I wanted to see how each amplifier performed.

The associated equipment was comprised of my Sonus Faber Stradivari speakers, WireWorld Eclipse Speaker Cables, WireWorld Eclipse Interconnects and WireWorld Silver Electra Power Cables. Each amplifier was connected to my APC S20 Power Conditioners. Each Power Conditioner is plugged into its own dedicated 20amp circuit. All amps used the exact same power cables, interconnects and speaker cables.

My sources were a Mac Mini running Audirvana + connected via a Wireworld Platinum USB cable to my EMM Labs DAC2X. For CD/SACD playback, I used my Oppo 105.

My preamp for this test was the Classe CP-800, an incredibly neutral preamp which I felt, would allow the sonic characteristics of each amplifier to shine. Plus, it was the only preamp I had at my disposal! The CP-800 is also currently John Atkinson’s (of Stereophile) reference preamp.

For each test, I allowed the amplifiers 30 minutes of warm up time. Although, it should be noted that the Classe reaches its optimum stable bias in only 20 minutes.

For each test, I wanted to keep the listening level at approximately 92db from my listening position. Using my trusty Sound Pressure Meter, I was able to ensure a fairly constant level between the three amplifiers.

Classe CA-2300

First up was the Classe CA-2300. This amp was purchased second hand from an AA member in October of this year. Prior to that, the amp had at least a good 9 months of burn in, driving his B&W speakers.

This is a stereo amplifier featuring the sleek new design from Classe. I am personally very fond of the new futuristic look.

On the back of the amp, Classe uses more traditional binding posts. They are not as well spaced as I would have liked, but I was able to get my WireWorld Speaker cables on without too much trouble. I would imagine someone trying to connect a less pliable speaker cable, could encounter some challenges.

The CA-2300 incorporates a cooling technology Classe borrowed from the Medical Device Industry. There is a small cooling fan which is only auditable when there is complete silence in the room. Once they music starts – regardless of level, the fan cannot be heard.

The first song in my play list, was Alison Kraus singing Lay Down Beside Me.
Right from the first few seconds of the song, I was impressed with how clean this amplifier sounded. In fact, as I continued well into my listening session, I kept scribbling down “clean” on my note pad. I must have written it down half a dozen times. Did I mention how clean this amp sounds?

The Classe stereo amp is one of the most neutral amplifiers I have ever had in my system. It continually displayed a perfectly balanced sound from top to bottom. Notes on the piano were some of the best I have ever heard. Each note was distinct and clean.

When it came to other instruments, each instrument appeared to have its own unique place in the sound stage with ample air and space around them. Voices were balanced across the sound stage, but noticeable recessed compared to the McIntosh 2301’s and Pass xa160.5’s

High notes were constantly clean and sweet. Drums had a crispness to them I’ve not heard with many other amps. Symbols just shimmered with such clarity that they were clearly the best I had ever heard.

The overall soundstage presentation was flat, void of any mid-range bloom, but it was also deeper than many other amps I’ve heard, truly driving deeper into the soundstage and was not so “in your face” as with some amps.

During my 2 hours, I experienced absolutely zero listener fatigue. When I exceeded 92db, I found that playing my music loud, didn’t seem loud because it was so clean and free from any sonic impositions the amplifiers may have made. I found the Classe amps got out of the way and let the sonic characteristics of the speakers shine.

The soundstage of the Classe was not as wide as the McIntosh 2301’s or Pass xa160.5’s. The narrower soundstage was quite noticeable on SACD’s and High Res Files. Where I have seen other amps literally push the physical boundaries of my speakers, the Classe stayed within them. As an example, when I played La Isla Bonita and Vogue by Madonna, other amps have had me literally looking over my shoulder and the impressive, near “surround sound” experience of these two songs. That being said, both songs, all songs in fact, sounded so good, it didn’t seem to matter.

I wondered if the narrower soundstage was attributable to the Classe being the only stereo amp in the mix. I would hedge a guess that the Classe CA-2300’s big brother, the CAM-600 monoblocks would hang with the other amps in terms of soundstage width.

The cleanness and crispness of the Classe amps was intoxicating. The speed of these amps on pop music, rock music, etc. had me doing some serious toe tapping. Home Theater Magazine called this Stereo amp, “the best sounding amplifier under $10,000”. I couldn’t agree more.

Pass xa160.5

Next up was the Pass xa160.5’s. I disconnected the cables from the Classe and hooked up the big Pass amps. I’ve had these amps for 11 days and I would estimate they have about 60 hours on them. They are clearly not broken in yet. Regardless, they were put into service for the test.

The Pass amps are extremely well built and they are stunning to look at. The pictures on the Internet do not do them justice. The black on the top is a rich, dark dark black. The front blue light is quite exquisite.

For those who don’t know, the meter on the front of the Pass amps measure the current drawn by the output stage. Unless the amps are driven very hard (and by much more inefficient speakers than mine), than the meters don’t move. Once the meters get past about two o’clock, you are entering class AB, or better yet, you are leaving pure class A. As hard as I’ve tried, I’ve been unable to make the meters move at all.

The Pass amps are pure Class A, delivering 328 watts of pure class A into 4 ohms. Beyond that, the amps can deliver considerably more power into class A/B, but distortion will increase as well. This is not uncommon.

The back of the amps are extremely well thought out. The binding posts are some of the best I have seen. There are large knobs and even big, bulky speaker cables would be no problem to connect. The balanced and unbalanced connections for each amp are located in the middle, near the top of the back of the amp. Easily accessible.

After a 30 minute warm-up, I began listening to the same playlist as I used for the Classe. Almost immediately, I could tell how the Pass amps differed from the Classe. The Pass produce a full, wide, rich soundstage which literally appeared to push the physical boundaries of my speakers, presenting the music which nearly pushes beyond the boundaries of the side walls. Impressive!

The soundstage was not only noticeably wider, but the amps continually delivered a rich, rich, full sound. The soundstage was full of rich texture which applied to vocals and instruments alike. Both had a tonal accuracy, which no other amplifier in my system has been able to produce.

The Pass amps provide a midrange “bump” with vocals and this bump dramatically increases as volume is increased. This bump and mid-range lushness is typically more associated with tube amps. Whereas the Classe appeared to be flat across the soundstage, the Pass amps put the vocals front and center. Vocals sounded almost three dimensional, and not unlike the 2301’s, dominated the soundstage at high volumes.

Bass was tight (but not as tight as the Classe), but the bass that was there, had a more realistic tone to it. It was not over-damped, but rather distinguishable. The bass drum sounded like a real bass drum, bass guitar sounded like a real bass guitar and standup bass was as good as I’ve ever heard.

Instruments had outstanding definition. You felt like you could almost reach out and touch the violin or acoustic guitar.

The upper frequency was smooth with excellent resolution. (NOTE: this was the biggest difference I noticed when I went from the stock power cords to the WW Silver Electra/Power Conditioner). The upper frequency lost all of the slight edginess that was present with the stock power cords and instead, became very very smooth with zero listener fatigue. I am greatly opposed to even the slightest brightness in sound and with the PC change, the 5% I had initially experienced with the Pass amps was completely gone. Bravo WireWorld!

The wooden percussion clap at the beginning of Madonna’s Vogue was clean and not irritating at all, unlike previous SS amps I’ve had in my system. The wooden percussion was not as perfectly defined as the Classe, but VERY close. Both the Classe and the Pass reproduced this sound with absolutely zero sharpness.

There was a wonderful flow to Amapola when I cycled through some of my Andrea Bocelli songs. The warmth, the texture, the ease at which the Pass amps presented Bochelli’s voice, was a realism unheard on the Classe, and equaling or bettering many tube amps (without the headaches and with a guaranteed consistency).

Whereas the Classe amp clearly displayed instruments with their own sense of space in the soundstage, the Pass was not quite as good as defining the location and providing that space. I don’t think it’s that the Pass did a bad job, quite the contrary, it’s that the Classe did such a darn good job at it.

As I cycled through the play lists and onto the CD’s and SACD’s, there wasn’t any type of music the Pass couldn’t play – and play extremely well. A romantic Andrea Bochelli song, no problem…they will romance the heck out of you. A driving song from Stevie Ray Vaughan. Not a problem. Rock on. A Yo Yo Ma solo performance. They take you there. A mesmerizing guitar performance by Paco de Lucia. I close my eyes and I’m in Spain! Everything I threw at them, they stepped up to the plate and hit it out of the park. Speed and a tight bass for rock, an incredible smoothness and silky midrange for Bocheli or incredible texture and detail for Yo Yo Ma and Paco de Lucia - it was all there in spades.

As my 2 hour session came to a close, I noticed just how much better the Pass amps got as they continued to warm up. They are very good from the second you turn them on, but they just get so much better as they warm up (and warm they get!).

McIntosh 2301’s

What can I say, that hasn’t already been said? Dan’s review of the 2301’s is here: http://www.audioaficionado.org/mcint...mp-review.html

The 2301’s are destined to become a McIntosh classic, like the 275. I agree with everything Dan has said about the 2301’s. They are world-class amplifiers indeed and it is clear to see why Harry P is using them in one of his reference systems.

As I began listening to Alison Kraus, I wrote down just how natural her voice sounded and as I moved to Andrea Bocheli, there was a noted soft, natural texture to his voice. As I moved along, Celine Dion's voice sounded so natural and completely void of even the slightest mechanical nature.

As I moved into some pop music, I noted that the piano notes (Alicia Keys Without You) didn't quite sound as clean and distinct as with the other two amps. Her voice however, sounded incredibly natural and sweet.

For a tube amp, the bass sounds excellent. No where near as tight and fast as the Classe. The Pass bass is tight and fast, but the winner - by a mile in that department - was the Classe. Despite that, the 2301's produced a good, deep bass. Not as fast as some people would like, but certainly excellent for a tube amp.

The soundstage on the 2301's bettered the Classe by a mile, and JUST BARELY fell short of the soundstage wide of the Pass. Soundstage depth was equally good on the 2301's and almost as good as the Classe. Running through the Madonna tracks, the 2301's produced that same "surround sound" affect I had heard with the Pass.

The 2301's went low, surprisingly low for a tube amp, but not as low as the Pass. The Pass amps appeared to have another octave with the room literally shaking. I had heard much lower bass from the Pass. The Pass could go lower and reproduce those lower tones longer. But that isn't to say the 2301's didn't hit the right notes when needed. They did.

The 2301's had the most natural tonal quality and was something you would expect from a tube amp. I continually scribbled down "texture", "tone", "color". All areas the 2301's excelled at and certainly bettered the Classe in this department.

The 2301's produced an absolutely beautiful, lush mid-range. Although I did feel that the Pass did an even better job (this surprised me), but it was very close and both the 2301's and Pass bettered the Classe in this area.

Where I felt the 2301's fell short, was speed. The lightening fast Classe and the fast Pass produced delightful transients, especially when playing pop or rock music. I kept wanting to pull the 2301's along, saying "faster, faster!" When playing ZZ Top, AC/DC, Stevie Ray Vaughan, I kept thinking "with these amps, my speakers aren't cut out for this type of music." The songs sounded a tad slow....like playing a 33 1/3 record at 32 rpms. That's just not where these great amps play their best. Where the 2301's shine was when playing some absolutely beautiful, flowing, graceful music - like Andrea Bocheli, Norah Jones, Diana Krall, Celine Dion, Barbra Streisand, etc. The 2301's are unmatched in their ability to draw you into his music and provide goosebumps. There is such a wonderful, natural flow to the way they reproduce music.

I enjoyed my two hour listening session, as I have enjoyed many hours listening to my 2301’s. I experienced absolutely no listener fatigue. They are world class amps in every way. They have an ability to draw you into the music like no other.

Are they perfect? No. They require tube maintenance (as does any tube amp) and sound may degrade over time as tubes begin to wear out. They are not quite as fast as most solid state amps, but they are certainly faster than most tube amps on the market today, likely in part due to their hybrid design. They undoubtedly present higher frequencies in the sweetest manner possible.

I would not be selling my 2301's, if I didn't have my eye on a pair of ARC REF 250's to go with my new ARC preamp. They are that good.

Winner?

So, is there a clear winner? No. Each amp has its own benefits and downsides. There is no one perfect amp. Choosing an amp is dependent on a number of factors, including, but not limited to, your speaker characteristics, speaker specifications, your listening room and most importantly, your listening tastes.

I could easily be very happy for a long time with any of these three amps. They are all world-class amplifiers in their own right. Two of the three are recognized as recommended components in TAS and Stereophile and other respected magazines and the third is well regarded in the market by its owners and by industry leader Harry Pearson.

When choosing between tube and solid state, we often have to make compromises or sacrifices between getting that last bit of grunt, authority and headroom which solid state offers or giving that up in exchange for the utmost refinement, delicacy, transparency and tonality which tube amps offer. While listening to the Pass xa160.5, I felt it sacrificed the least, while providing me the best of both solid state and tube amplification.
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Last edited by mbovaird; 12-09-2012 at 12:11 PM.
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Old 12-09-2012, 01:45 AM
joeinid joeinid is offline
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Absolutely wonderful job Mike. I take back everything bad I said.
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Old 12-09-2012, 01:46 AM
mbovaird mbovaird is offline
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I would have liked to have had the review done sooner, but you know...it tis the season and there is plenty to do.
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Old 12-09-2012, 01:46 AM
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Most Impressive review Mike, Thanks!
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Last edited by Masterlu; 12-09-2012 at 01:48 AM.
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Old 12-09-2012, 01:48 AM
mbovaird mbovaird is offline
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Thank you Ivan.
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Old 12-09-2012, 02:17 AM
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Great Review Mike!........I like the way you complimented both amps without swaying either way to strongly......
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Old 12-09-2012, 03:01 AM
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Mike... Thank you for the review.
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Old 12-09-2012, 03:04 AM
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[QUOTE=mbovaird;408116]Background


I noticed just how much better the Pass amps got as they continued to warm up. They are very good from the second you turn them on, but they just get so much better as they warm up (and warm they get!).


same here mike
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Old 12-09-2012, 03:37 AM
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Great write up Mike, obviously a lot of work, but I am sure a lot of fun too!

Thanks for sharing your journey!
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Old 12-09-2012, 03:58 AM
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Mike...wonderfully done. Thx so much for sharing your thoughts on your amp shootout. What a fun read
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