Pass Labs amps questions

SO i started looking into Pass brand amps.  My room is carpeted movie theater of rectangular shape, 18 wide x 26 ft deep.  I'm currently running Audio Research 5SE into Mark Levinson 331 (100 watt RMS SS at 8ohms) then Dynaudio Confidence C4 speakers.  Although I love the sound this gives me, i feel it just doesn't have enough oomph!  For example, in order to sound "right" when i listen to the Eagles Hell Freezes Over DVD, volume is at level 60 on the 5SE.  Im not detecting any clipping at all nor does the Levinson get too warm.  I don't think its straining at all but not sure how to tell.  Its old and i just want to try and get a different or maybe see if i can get a better sound.  I am wondering what the audioafficianados out there would recommend or provide more info on with regards to the Pass Labs line up.  I am specifically wanting a pair of Class A mono blocks.  What falls in my budget is a pair of the XA200.5's on the Agon site here now VS a New/Demo X350.8 demo from Reno Hifi.   Would the X350.8 hold an advantage over the 200 monos with its additional 300 watts of power (C4s are 4 ohms)? I remember needing to double the power in order to move the SPL 3 db???.   If this were correct and given my room size, would this added power benefit my system? All in all would you prefer used pure class A less power or brand new class AB higher power for about the same price?  I'll sit and *listen* for your knowledgeable replies.  Thanks in advance.
I agree that you are on the right track. I have owned Dynaudio before and have listened all the way up their line at various audio shows. They can be difficult to drive without good clean power. I would not consider anything less than 250wpc doubling to 500 into 4 ohms. Class A or Class A/AB. I have had good synergy with McCormack, CODA, Plinius, ModWright, SimAudio and Jeff Rowland.

Good luck in your search!!
+1 for the XA200.5’s.
Being the XA it will have more classA bias on it compared to the X series, and therefore should sound sweeter. And run hotter, than the X (you pay a little for that extra sweetness)
The C4’s are 90db and a fairly easy load, so the 200watts of the XA200.5 which probably puts out more like 250w should be ample for big level.

Cheers George
" I don't think its straining at all but not sure how to tell."

You listen to it. If an amp is straining, its very easy to hear. 

" Although I love the sound this gives me, i feel it just doesn't have enough oomph!  For example, in order to sound "right" when i listen to the Eagles Hell Freezes Over DVD, volume is at level 60 on the 5SE. "

Before you go any further, you need to look at the source. I don't know what DVD player you have, but its most likely  a bottleneck. If you don't start with a source that has the qualities you need, the rest of the system doesn't matter. You can't amplify what's not there.
I'd choose the XA mono's over the X350.8 although both are excellent.  The XA amps are really something special, and once you get a taste of Class-A operation it's hard to get enough of it.
some listeners prefer the X series to the XA   you just gotta listen    contact Pass, they will help you decide based on your preferences
chenglo1, the latest  0.8 from pass are more resolving than previous 0.5 and considered by many improvement over 0.5 and they build some better. Even the new furutech binding post are something special. Also you for sure are missing what your speakers can deliver. Plus you have a great pre-amp that many people using with pass. I would work with Mark from Reno HIFI. He will be able to get exactly what you want. Try both class A and class A/AB and see what you like best in your system. Don't just settle on XA 200.5 (even so they are very good). Work with Mark on auditioning newer 0.8 series. His demo policies are terrific. Working with him you be able to get what you like best.
I also agree on a comments about source. if you are using some cheap DVD based source like Oppo, you will not be able to hear what your system can deliver. To match your speaker and pre-amp level you will need a very good source. Esoteric cd players or DACs known to have a great synergy with pass amplification. Latest X series from esoteric are big step forward towards musicality and natural sound.
When I heard the C4 Platinums driven by the XA60.8 monos the needles never moved even though we played at quite loud levels. More powerful than you think.
I strongly recommend that you audition the .8 series before purchasing the .5, just because its Class A.  I recently upgraded from the Int 30A, their Class A integrated, to the Int 60, their Class AB integrated.  Not quite the same as what you are talking about but close enough for me to say that I think you'd be doing yourself a great disservice by not at least trying the .8, even if it is Class AB.  Not quite as sweet sounding, but hands down the better amp in every other respect.  Plus the C4's which I am very close to purchasing and have spent quite a bit of time auditioning really don't need as much power as people seem to think.  So you might want to rethink the power issue as well.
Well fellas, thanks for all your input. I settled on a pair of XA200.5 off our host site here. After reading the reviews out on the web and opinions on the forums, i’m confident it will be a worthwhile investment. Not to mention that it should be a significant improvement over what i am currently running.

With respect to my source, I have a custom built media PC with high end sound card sending signal via SPDIF output using Transparent Reference digital cable to WYRED DAC. Transparent Ref balance cables to AR 5SE, Transparent reference to Levinson 331 and finally MIT Shotgun MA speaker cables to C4’s (haven’t tried Transparent Ref spark cables yet believe it or not-had just upgraded from Transparent Ultra). I used to run a 3500.00 Denon DVD audio player (circa 2005?) but retired it because the sheer advantage of using a media PC that can play my DVD music, HD files, CD’s in WAV format and youtube when guests are over. Yes, poor quality but nice when one is entertaining and someone really really wants to hear his or her song from youtube! However, you have got my attention and perhaps i should invest in an updated CD or DVD player to experience my components full potential. I’m now getting back to familiarizing myself with old music that i used to listen to a lot in my younger days. Preparing my ears for when the XA’s arrive. I’m excited is an understatement!!!
You have "settled" on a very nice pair of amps.  If/when you decide to upgrade again, try the .8's

how do you like the synergy between the ARC Ref5 SE and ML power amp.

I like the ARC Ref5SE and feel it is the best tubed pre-amp at the present.
I believe that you are the 1st person to post about using this special combo.

Happy Listening!
2nd Note;
Transparent cabling is a sonic match for your gear, ARC/ML/Pass Labs,
it will really bring something special to your system!

If you can go all out on Ref XL or the mighty OPUS, you will be rewarded!

I actually had a X350.8 with my X350.5 Amp together at the same time in my home. It was great to demo the X350.8 in which I was considering trading for and purchasing. The X350.8 was provided courtesy of Reno HIFI.

To me, and my system, the X350.5 was far superior in openness and soundstage. The .8 version was very dark sounding. Now this was when the .8 series just came out. I returned the .8 back to Reno. Soon after that, Pass stopped advertising the X350.8 in there line up. I think they also thought something was wrong.

It appears that they have since fixed what ever was wrong and now many report the X350.8 to be the better unit.

Good choice. Here is a group review of the .5 vs .8 looks like they just preferred the .5

A group of us compared the XA100.5 vs XA100.8 at a friends place. ARC REF5SE preamp. Sonus Faber Stradivari speakers. WW Platinum Eclipse speaker cables and IC's. Source was a Meitner MA-1.

The .5's were the unanimous winner....but the .8's definitely had some positives.

The .5's sounded fuller, with a greater sense of tonality richness....definitely more tube like if you will.

The .8's had tighter bass, but more bass, which ultimately created problems in his room. The .8's had a greater sense of speed and dynamic punch. I personally felt like they sounded more like a traditional Class A/B amp....but with some nice goodies thrown in.

It definitely was closer than you would think. But, at the end of the day, with his associated gear and room, we felt the .5's edged out the .8's.
Cheers George
Pass 350.8 has better imaging,better bass detail and more dynamics than 350.5  thats just what i hear. Enjoy!!
Pass labs and Reno hi FI customer service is second to none. Congratulations on your purchase. 

I directly compared my XA160.5 to a pair of XA160.8 in my system.   I preferred the .5.  It was more natural sounding in my system, more believable with a better sense of presence.  The .8 sounded slightly mechanical, artificial and somewhat flat.  They emphasize the leading edge while the .5 emphasize the decay.  The XS combine the best of both, IMO.  I'm sure it is very system dependent.
Why would they have a 350,8 if it wasn't better than the 350.5?????
I'm running a X150.8 in a room that is 13 feet by about 20 feet.  It could fill a much larger room without breaking into a sweat.
I have always loved Nelson Pass' equipment, but I also believe that the John Curl ML equipment designed ("JC" in the model number) to be excellent. If you can find it, any Class A Audire equipment is truly superb. The only real advantage of mono blocks us that you can either hide the amps or be ostentatious.


Did you give serious break-in time to the XA-160.8s on trial? I haven’t compared mine to .5s, but after a rather long break-in and some substitutions of PCs and platforms, I find the XA-160.8s excellent in all respects: extended and linear across FR, ample width and depth, accurate pitch and timbre, and most of all, vanishingly low distortion and black background that in some systems might be confused with a loss of airiness. Not mechanical or artificial at all.

+1 EBM, but consider as well that Pass keeps both .5 and .8 series in their catalog.

I don't see the .5 on Pass website, only Xs and .8 amps

In my system, all listeners preferred X250.8 to X250.5,  same in friends system when he upgraded


Indeed. They showed both series for awhile on the web site, but no more. 

Having heard a variety of Pass equipment, I would heartily and in fact, strongly agree with Georgelofi, Ozzy, Marco1 and l35: you have to hear ANY component in your own system, and in your own listening room.

I happened to hear the .5 and .8 comparison in the above-mentioned system. The amps were compared fairly, each given time to reach optimum operating temperature and the comparison was A-B-A, which I feel is a smart, fair / intelligent way to listen for a comparison. It takes longer but is both more informative and gives each component a chance to show its strengths, relative to the other item in the comparison.

Components can, in my estimation, only show their true character when placed in a room that has been carefully and fully treated for its inherent sonic signature. So turning to Marc at Reno HiFi is a wise choice. He is Great at helping you find what makes your heart sing --after you get your system to 'sing the room' his advice will give you even more satisfaction.

Best of Luck --and Patience. In my opinion they will both pay off.
Hi,Wonderful review of PASS 350.8 in Positive Feedback #87 by Robert Youman.I totally agree.
I owned different Pass Labs poweramps and monos in the last 7 years of time. I also owned the XP-20 for 2 years of time.

I owned the XA100.5 for 2 years of time as well. Now I own the X350.5. I use this one with the latest Purist Audio LE luminist powercable. This gives the 350.5 a totally different level. The mid freqeuncies are more souding like they do with XA series. ( I owned 3 different XA power amps of Pass Labs) I love the extra controle and details the X series can give.

We did a test with the AR 5SE pre amp with the X350.5. People think it is a very good preamp, but mannnnn it is a very poor pre amp.

What did it do connecting with the X350.5?

- the speed, controle en timing went to a much lower level.
- the details became a lot less
- the stage depth and width became a lot less
- the individual focus of instruments and voices became less sharp.

Not even for free I would use the Audio research ref 5SE as a pre amp. The person who owned the AR Ref5SE could really cry. I never forget the look in his eyes. The truth can be hard and confronting.

My personal opinion about Pass Labs is they create stunning poweramps and create good pre amps. But not stunning ones, as they should be. They are not good enough. But AR pre amps ar not better!!

* my next Pass Labs will be 350.8, but probable the X600.5 monos.
" My personal opinion about Pass Labs is they create stunning poweramps and create good pre amps. But not stunning ones, as they should be. They are not good enough."


I agree. My Pass amps were definitely at a higher level than Pass preamps I've owned. But you don't give an alternative. If not Pass or ARC, what preamps do you like with Pass amps?
That is a good question. I had a lot of email contact with Desmond Harrington (President Pass Labs) between 2009 and 2015.

In 2009 I said to him; Pass Labs needs a more realistic focus of instruments and voices. I call it intimate focus. Because instruments and voices are in real very direct and small in proportion.

I owned the XP-20 for 2 years of time. It is a good pre amp, but good never will be good enough in my world. Only the best counts and the rest doesn’t matter.

In 2010 I started research in measuring the acoustics. I created Statement Audio Pro measuring. In 2012 I bought an Onkyo PR-SC5509 pre amp. With my measurement in 2012 I already could outperform the XP-20.

I told Desmond about it, he wanted to buy and test one for himself. I said without my knowledge and insight it does not make sense at all. I had to laugh because it is a new and different way of using and thinking about audio.

I improved the way of measuring in the last years a lot. We modified and used new parts and techniques inside the 5509. We used for about 2500 euro on parts inside.

I use the beste digital lasers and we work so much more precise than the way people work in audio. Now we are at a point we will sell the way of measuring and the techniques we created.

It will bring audio to a much higher level than people know at this moment. It can create a much higher level out of a Pass Labs poweramp. You cannot compare it with a XP-20, it is superior in all parts you judge sound for.

You can create stealth low frequency with it. This sets a subwoofer in phase with the loudspeakers. But the energy is exactly were it is at the recording. Even when the subwoofer is 3 metres from this part.

It eliminates the acoustic problems in a room, but it also is able to let you hear much more details of a recording. This year I have done a lot of research in diversity in sound. Because this is the most important part to create emotion in music. Even in a worse acoustic you can create a sound you never would expect be possible in that kind of room.

With different parts and measuring we are able to create more diversity in sound. This will let you experience more emotion during listening. It reveals much more diversity in sound of voices and instruments.

Based on a much better timing the energy of strings can be felt in the air. It gives instruments and voices a real 3D shape. My clients call it an addictive sound.

Audio is being created by trial and error. I call it: audio cambling. Because is owns no foundation why the sound and stage is what you hear.

That is why we work by Tru-Fi. These are 8 parameters you judge sound for. By labeling each part in your set on properties you can understand why the stage and sound is what you hear.

When an audio system owns all parts of Tru-Fi it always owns a higher level of emotion. Because Tru-Fi is based on the human emotion.

The emotion is inside of the music. And you need the right properties to be able to let people hear these properties which create the emotion of the music.

That is why we build an audio system by properties. This allows us to understand why the stage and sound is what we hear. This makes it so much more effective than any kind of trial and error.

The Pass  first watt if you have efficient Loudpeakers the F6 .I had a SE model built  using  premium parts VH audio output caps.My speakers,Salk Budd Fried -SE  are around 89-90 dB but 4ohm.
With my amp 25 wpc 8ohm, double that  50wpc into 4ohms  my amp using Jensen Input transfotmers , Matched Jfets,  and Mosfets outputs a true Dual mono design.I have plenty of power running in pure class A .
Very detailed warm and musical. 

Thanks! for sharing- All

Happy Listening!

A few years ago I ran C4s with 250.5 and loved it,Ive heard the .8 amp...either way your going to enjoy,I guess it just depends on your budget .
I agree. My Pass amps were definitely at a higher level than Pass preamps I've owned. But you don't give an alternative. If not Pass or ARC, what preamps do you like with Pass amps? 

I like tubes somewhere in the system.  I use an Ayon Pre with my X150.8. The Ayon has 6H30 tubes and I am not going to change any time soon.
i would agree that pass labs preamps are not quite as good as the amps...i think it's time for an update of sorts...perhaps wayne (he designs the preamps, not nelson) is working on that right now...