jgm

Overall Rating
 5 of 5

Value Rating
 5 of 5

Used product for
1 to 3 months

Visitors rate this review
5.00 of 5, 1.00 votes

Price Paid:  $3250.00 from Reno Hi-Fi

Summary:
I heard one of these driving big Tannoy's when they first came out and the sound was captivating. I have been searching for one on the used market and found what I consider the deal of the century. This amp just doesn't have a signature that I can identify. After living with this ampfor several months, I now understand why some reviewers had difficulty describing how these amps sound. Stone neutral is the only way to describe this amp...easily qualifying as the most neutral amp I have yet owned. I purchased this unit as a freshly "refurbished" unit. I have had it for several months and I still have yet to find something beyond it's hulking frame to identy it. The one thing this amp does well (for better or for worse) is reveal the rest of the chain. This amp places everything else in your system clearly under the looking glass. The good and bad of such a revealing and neutral amp are obvious: it will force you to re-evaluate your playback chain and will lead, most likely, to more purchases as you realize colorations in other component you hadn't noticed previously.

What can be said about this amp's character? Limitless power. Bass is tight, deep, authoritative and limited by the loudspeaker (in my case, Acoustat Spectra 2's). The highs are again limited by yoiur source components and loudspeakers but is never strained, etched, glaring, or biting. The feeling is extended and relaxed. The midrange is as good as the rest of your system allows...here, the amp just has no character...it is just absent. And music - forget about it. If you like it, you play it and you'll love it. Percussion...human voice...piano...strings...rap...techno...full orchestra...rock...the amp loves it, all of it and you will too. Loud, soft...it doesn't matter to the amp, only to everything else in your chain. I have yet to find an instrument or genre the amp won't handle is if it weren't there.

The main problem with this amp is, paradoxically, a direct result of its best qualities: it is so neutral and revelaing that I hear to a greater extent the limtations (flaws) in my front end and in my speakers...and this will ultimately lead to replacement (more purchases). Moreover, I think I will be forced to chose even more carefully new components that provide equal neutrality.

Build quality is second to none. The amp does give off heat and is heavy, but you can move it by yourself if need be. The only real criticism I have is in regards to the binding posts. They are alligned in such a way that the rear panel carry handles will get in the way of some cables with spades (I had a very difficult time with my PS Audio Statement bi-wire).

Overall, a tremendous product and an absolute bargain on the used market. This is the kind of amp you get to never replace.

Strengths:
1) Neutrality!
2) Neutral
3) See #1 and 2 above, repeat.
4) Highly revealing of all other components in the playback chain
5) Pride of ownership
6) A way out of the endless cycle of upgrades (at least for power amps)
7) Extremely wide and deep power bandwidth
8) Suitable for all forms of music
9) Probably only a few speakers on the planet that it might not drive to full volume
10) a HUGHE bargain if you can find one on the used market

Weaknesses:
1) Big, heavy and warm
2) binding posts may not accept some stiffer speaker cables with spades due to carry handles on the back of the unit
3) forces you to re-examine the rest of your components since their flaws will be revealed

Similar Products Used:
Classe' CA-301 and CA-101, Jeff Rowland Design Group (JRDG) Balanced Model 5 and JRDG Model 2 with BPS, BAT VK-200, CODA Continuum Stage 3.2, Mark Levinson No. 29, Counterpoint SA-220, Adcom GFA-5500 and Musical Concepts Modified GFA-555, Hafler XL-280.

Price Paid:  $0.00 from high end research si

Summary:
MY SEARCH FOR A AMPLIIFIER IS OVER.ABOUT 6 MONTHS I CAN.T FIND ANY WEAKNESSES.THE REASON FOR THIS REVIEW IS TO SHARE WITH PASS LABS OWNERS OF HOW TO GET THE BEST OF THIS AMP. OR ANY PASS LABS EQUIPMENT.ONE DAY MY AGENT IN SINGAPORE SHOWED ME PHOTOS OF PASS LABS IN THE DEMO ROOM WHILE TOURING THE FACTORY IN U.S.I SAW THE WHOLE SYSTEM WIRED UP WITH NORDOST CABLES.I QUICKLY WIRED MY WHOLE SYSTEM WITH RED DAWN INTERCONNECTS & SPEAKER CABLES.MY WHOLE SYSTEM OPENED UP AND THE FIRST TIME THE SOUND I HEARD IS EMOTIONAL & HAUNTING. I HAVE TRIED VAN DEL HUL SCS6.AUDIOQUEST DIAMOND.WIREWORLD SILVER ECLIPSE 3 ETC.ALL OF THEM AS GOOD AS THEY ARE CANNOT MATCH THE NORDOST CABLES IN A PASS LABS SYSTEM.

Strengths:
EMOTIONAL & HAUNTING.

Weaknesses:
I WISHED I HAD THE SPM OR BETTER STILL THE VAHALLA IN THE SYSTEM.

Similar Products Used:
TOO MANY.

Price Paid:  $5256.00 from 2nd hand shop

Summary:
Equipment in use:
Pre: Sonic Frontier Line 3, tubes changed to Telefunken ECC88.
DA : PS Audio SLIII
CD : Marantz CD19
Spearker: B&W Nautilus 803, KEP LS3/5A Piano Black
Cables: Audioquest Exterme Clear, Taralab Air-1 and CARDAS Netural Reference.

I have used the amplifier from Nelson Pass for many years. Started from the Adcom 555 to Threshold T100 , T400 and then PassLabs X350. Since It is too great and nobody would sell it, I needed to spend also a year to book for it from 2nd hand market.

The 1st CD that I played with this amp was piano. I could hear the difference between X350 and T400 although the amp not run-in. I could clearly see how the pianist press his fingers on the piano any play the music. Very detail and accurate!! At the same time, the bass become more controled and more punch when compare with T400.

Strengths:
Accurate, dynamic, resolution, deep bass, quiet and transparent

Weaknesses:
midrange not sweet enough. resolution a little bit not in detail in midrange.

Similar Products Used:
Mark Levinson 335, 336.

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Summary:
I have owned too many gears, my wife called me an "equipment-phile" instead. With Sonus Faber Extrema and Dynaudio Confidence 5, I can't enjoy music unless music are amplified grainless.
I am not a solid state person, so I knew shopping would not be easy when I ran out of power on my Sonic Frontier Power 3 (best sound/value tube amp on earth). First came Classe, it has everything I dislike about solid state - edgy top and thin midrange, music sounded coarse. Levinson was smoother every where, but music sounds "sterile" and no soul. Krell brought back the rhythm, but also added some annoyance on top and mid. McCormack was surprisingly good for the money, but reliability was an issue and factory was not helpful to correct my problem. Last came the Pass X350, the first solid state amp that does not remind me of solid state. It has incredible dynamic, coupled with SF Line 3 and Sony SACD player, so every listening session is a new experience. Bottom end is close to the best, but I am not a bass freak and even tube amps can satisfy me. What matters the most is top end; my ears have been spoiled by tube amps and Pass is able to reproduce that inner details without harshness or grain. But nothing is perfect and it also applies to Pass X350. Midrange can sound lean on some system, so careful system matching is required.

Strengths:
Dynamic, transparency, resolution

Weaknesses:
Too accurate

Similar Products Used:
Krell, Levinson, Classe, McCormack, Bryston, Sonic Frontier, Audio Research, and some others

Price Paid:  $5000.00 from Pre-owned

Summary:
Driving Martin-Login Monolith III (hybrid ELS + sub). Bi-amping, Pass drives ELS panels, B&K drives subs. Sony 777ES drives passive preamp which drives M-L electronic crossover which drives Pass and B&K amps.
I listen at low levels for hours during the day on weekends, and on weekend nights, we often turn out all lights and let it crank to realistic volumes with primarily jazz, rock and blues music. The Pass has a big sound, which may be another way of saying that it is very dynamic. It is also extremely clear and clean without a hint of grain or grit. The M-L panels drop to under 1 ohm at 20KHz which has a way of shutting down lesser amplifiers (I have returned several big well known amps due to this), but the X350 is unfazed.
The resulting stereo image is wide and deep, the inner detail is awesome and the slam produces goose bumps in my medium size room. The sound is very similar to good tube amps - crystal clear mids and highs except the Pass has far deeper and tighter bass and any tube amp. Speaking of bass definition, I discovered a little secret of the X series amplifiers ...
I am an electrical engineer and I studied Nelson Pass's patents and circuitry very carefully. I noticed that, yes, there is not feedback at the output stage, and there are no DC servo loops but as a result, the output stage bias current and offset voltage can drift over time and temperature. I contacted the factory and obtained a service manual. I have o'scopes and DMMs all over my house, so I opened my (6 months old - purchased used) X350 and measured the Class A bias and offset voltage. Sure enough, they had drifted from the intended factory settings by more than 40%!! Since the amp runs very hot, I decided to allow it to stay on 24/7 in order to thermally stabilize - which took 3 days! Then my bias and offset adjustments that I made every 6-8 hours (for 3 days) started to settle down. On the 4th day, I did the final adjustment, tightened down the lid screws and sat down to listen. The bass was much tighter, the bass stereo image was much more focused and the very highest treble octave was a little more open. An obvious improvement, well worth the effort. This occured even though the B&K amp drives the subwoofer (150Hz crossover to ELS panels). So the biggest definition improvement was in the X350/ELS panels upper and mid bass region down to about 100Hz. WARNING! This adjustment should only be performed by a trained professional. If you attempt do this yourself, you run a very real risk of electrocution and blowing up your $9K amplifier! I might suggest that many of today's "zero feedback" power amplifiers and preamps could stand the same adjustment in order to maximize their sound quality.
I also found that huge wire is required by the big Monolith speakers, 4AWG on woofers and 8AWG on the panels. This results in full dynamics with no compression even at high volume levels.
I built a very sturdy wooden amp-table with wide carpet wheels in order to move this 125+ pound beast around in order to wire it up and service it. This table sets about 9 inches off the floor and allows the huge heatsinks to completely overhang so that they suck in (via natural convection) plenty of air.
The blue LEDs in the panel get a little old because blue is so very intense especially when all the other lights are out - and you can't just remove the LEDs (I tried) as they are actually part of the bias circuit!

Strengths:
Transparent, dynamic, quiet, liquid, detailed, can drive 1 ohm no sweat.

Weaknesses:
Runs hot as H. Its heavy as H.

Similar Products Used:
Cary Slam-100, B&K Reference, Marsh A400