Pass XA.60.5 Monoblocks to Pass XA.100.5 Monoblock

I had written a review of the Pass XA.60.5 Monoblocks so rather than do another complete review, I thought it might be more informative to discuss the differences I have experienced when I recently upgraded to the Pass XA100.5 Monoblocks. I had asked for feedback on Audiogon about making such a change and would like to address some of the responses I received (and appreciated) now that I have had the real world experience of listening to the new amplifiers. I always have mixed thoughts about component burn in but for the sake of clarity, I have over 300 hours on the new XA 100.5 monoblocks. All of the other components and cables have remained the same from the time of the previous Pass XA60.5 monoblocks. The room is the same, my living room, which is 12 by 23 with the loudspeakers on the short side about seven feet apart, fifty six inches from the wall behind them, and about 2-3 feet from side wall and staircase on the other side. Certainly, not a perfect room, but we do the best we can with what we have. I will say that I have had systems in much larger rooms years ago and personally have been able to achieve better sound in a smaller room given imperfections in all the rooms I have had my systems in.

I should again mention the loudspeakers as they are a very important factor in the determination of the match with amplifiers. I have Tyler Acoustics/Woodmeres which have a sensitivity of around 89-90. These are fairly large speakers that are 4 ohm and have two 10 inch bass drivers, 2 seven inch mids, and the tweeter and are all SEAS drivers. If you look at the system photos, you can see the speakers. They can take a good amount of juice and the drivers react to any kind of component change I have made over the period of time I have owned them.

Some of the issues I will discuss are the following:
*2db change from Pass XA60.5 to Pass XA100.5
*Stereo XA30.5 to XA60.5 to XA100.5-"sweetness of the sound"-concept that you lose some when you increase the power of the amp
*Soundstage and Imaging Details
*Bass (quality and quantity)
*Weight and Fullness of Sound
*Knowing what I do now, would I make the change again with the current information and knowledge?

2db change from Pass XA60.5 to Pass XA100.5

One of the thoughts that was expressed to me about the upgrade was that a 2.25 db change would mean nothing and the sound would not be very different. Well, the change in power makes a difference and in my case with my speakers in my room, makes a big difference. With the XA100.5, the system has the capacity to play very loud and at a very high quality but the bigger change is at lower listening levels, and normal listening levels. My music, whether rock, classical or jazz sounds more lifelike through the complete sound spectrum, highs to the lowest bass. The XA100.5 have the capacity to drive a more demanding speaker. Mine are somewhere around 89-90 4ohm( not inefficient) and the ease of the XA100.5 to drive them is highly evident. The XA60.5 did not take control of the speakers in the same way and the XA30.5 was not able to match well with the speakers due to the lack of power. Could one live with the XA60.5 and my speakers, in a word yes. It would be someone who does not push the amps by playing them loud at times or have the kind of music that tends to have dynamic swings. In my experience with the XA60.5, I pushed them enough that they went into A/B a fair amount of the time. Truthfully, I think the XA60.5 Monoblocks would be better with other speakers that are easier to drive.

Stereo XA30.5 to XA60.5 to XA100.5-sweetness of the sound-concept that you lose some when you increase the power of the amp

I read threads where audiophiles comment that the XA30.5 is the sweetest amp in the XA line and when you go to the higher powered amps, you lose that sweetness. Well, that is just not true in my experience as someone who has owned half of the XA line. The XA60.5 and now the XA100.5 have every bit of sweetness that the stereo amp had. I don't feel I lost anything in this area with the higher powered amps. I wonder if those who believe this have really heard many of the amps in the XA line. I have not heard the XA160.5 and the XA200.5 but if you have concerns about upgrading from the XA30.5, in terms of losing the sweetness of the sound, the mono blocks will give you all that you get from the XA30.5 and more. That is my opinion from owning these amps. My bias over the years has been to monoblocks. I think they drive the speakers with more ease than a stereo amp but that is always open to debate.

Soundstage & Imaging Details

The soundstage is wider than with the previous amps. I hear more sound coming from the sides behind the speakers. The images are more focused as if a lens has sharpened the picture. I hear and feel the separation on stage with all of the instruments and sometimes with the XA100.5, I am actually fooled as I hear things that I have not heard on a particular CD and it takes me a couple of seconds to realize that the particular CD was generating that sound. I actually have thought that something else was going on in my room. In addition, I hear more of the subtle information with the XA100.5 vs the XA60.5. I mean hearing the breathing of the performers and background instruments that I have not heard previously. The bigger amps pick up those nuances in the music much more than the other XA amps I owned. The images are bigger and fuller and that improves the presentation of the music.


The Tyler Woodmeres have the capacity to go pretty low and with the XA100.5 amps, there is an increase in the amount of low end that I hear. I can better differentiate the lower note details . The bass is more realistic using the XA100.5 than with the other XA amps I owned. Of course, if you have a loudspeaker that does not produce and deliver much of the low end, no amp is going to make that appear. The loudspeaker will need to have the ability to go low. Many speakers I have owned, quality loudspeakers, did not go very low, and the amp change would not have affected those speakers.

Weight and Fullness of Sound

Now we are getting to the core of the change and the biggest difference I experienced so far by upgrading from the XA60.5 to the XA100.5 monoblocks. My system is getting a much bigger sound in terms of fullness and weight. The smashing of the drum kit seems more realistic to me. On many of the recordings where there is much percussion, I can better imagine the drummer really hitting a full drum kit. All of the instruments have a larger, more realistic sound, including voices. The whole sound has a more weighty feel to it and that gives it a more realistic feel than what I previously had. Its hard to convey these changes without someone hearing the two sets of mono blocks but the XA100.5 give a bigger sound to the system and a thicker deeper sound to the system. These amps are taking more control of the drivers and the sound reflects that.

Knowing what I do now, would I make the change again with the current information and knowledge?

Well, as one goes up the XA line, one pays the price for the more powerful amps so there is always the question of whether the upgrades are worth that extra money spent. It hard to put an exact per cent in terms of improvement. All I can say with system component changes is that I have tend to have one of two reactions. One is that the effect is minor and not worth additional money and the other is that the change is great enough that I want to keep the new component and it is a significant improvement to my system. This change from the Pass XA60.5 mono blocks to the Pass XA100.5 Monoblocks is one of those significant changes. I am getting so much more from these amps and the system is playing at a higher level which is really all I can ask from a component upgrade. Again, it is always system dependent. I think that if my speakers were not as power hungry, the change would not have impacted to the same level. I have found that my Tyler Woodmeres are very sensitive to component changes which helps in evaluating what is happening. I have noticed this with amps as well with sources. I was surprised how much the system was effected by changes in the CD source when I tried about five different players in the system some months ago. And last but not least, the room is many times the biggest component in the whole system. It effects every aspect of how the system sounds including the amplification. I certainly do not claim to be any type of expert in the audio world. I have learned whatever little I know by trial and error. As you can see from my posted system (Forever Done, Never Done), I have gone through a great number of components. My opinions are only offered so they can be of some kind of assistance to someone else who may have some similar amp choices to make. To be honest, I am hooked on the XA line of Pass Amplifiers. I have owned many amps and they have all had many fine qualities but the Pass XA line is something very special to me. Yes, they do use a fair amount of electricity but once burned in, I leave them in the standby mode. They have an alluring midrange, a wonderful transparency, image really well, give me very good low end, and play with an ease and smoothness that allows me to listen for hours. The Pass XA line is very unfatiguing and that makes a big difference to me. My music listening is my therapy. I work in a conflict management role and when I come home from work, i can be listening for 3-4 hours a night and much more on the weekends. My living room is my stereo room. (one advantage of living with just my dog, she is very tolerant) For a frame of reference, other amplifiers that I have had in my systems over the years included Simaudio Monoblocks (500 watts per channel), Musical Fidelity Nu-Vista Integrated, Musical Fidelity Tri-Vista Integrated, DK Design Integrated, Pathos Acoustics Logos Integrated, Bel Canto 500 Monoblocks and Bel Canto Stereo 500, Conrad Johnson Stereo Amp, Adcom 555, B&K Inegrated, NAD Integrated, and probably many others I can't remember at this point.

One last point on this thread. If you have a different point of view related to anything I wrote or anything responders to my thread write, that is terrific. All I would ask is that we are respectful of each other. I get tired of reading threads where people are not respectful of each other. You may have more knowledge about Audio than myself or someone else, but the connection to educate someone or just reach someone through communication cannot be effective unless we are tolerant and accepting of one another. I hope new people want to get into high end audio and I hope some of those people want to have a 2-channel system. We need to cultivate that interest in the high end. Snobbery, intolerance, being condescending and sarcastic, does not foster positive relationships. I hope others will get into High End Audio and that is up to us to encourage. Thanks for taking the time to read this whole thread and I look forward to any responses from potential Pass XA amp owners, current Pass XA owners, or anyone who else who wants to share their thoughts.
I am sorry for any typos in my comparison but wanted to get it on Audiogon at this point. I checked it a few times before posting but just noticed a few. Also, I would like to thank Mark at Reno HiFi for his assistance in the process. I know many dealers get a bad rap but Mark is one of the good people in Audio. He takes the time to answer questions and is always willing to discuss anything related to the world of Audio.
Thank you fora wonderful & informative review. Your results are expected. Even with more efficient speakers. I have been told by a few the XA100.5sare the "sweet" point of the line. Enjoy them. I am curious about the 200.5s.
Nice job, I'm confident it will be appreciated by others considering the purchase of these amplifiers.
Yes, as expected, all other things being equal or nearly equal, more power is better especially with multi-driver speakers. I wonder if the result would be the same with my speakers that have one 8" driver and 1" silk tweeter? Most likely yes.
Do you wish to increase the power even more and try XA200?
Great review Pettyfeversk. Thanks for taking the time to write it. Your experience is very similar to the one I had when I switched from the XA100.5 to the XA160.5. My speakers are harder to drive than yours, so the 100.5 was not enough power.

I have found that each time I have moved up the Pass line, the sound has improved. This was also true IME with the Aleph 3 to the 5 and then to the Aleph 2 monoblocks. I found everything improved, especially a sense of openness and effortlessness as well as control over the lower frequencies.

Enjoy your new amps.
I TRULY APPRECIATE your enthusiasm for music appreciation after you come home from work to decompress. so many folks just switch on the television and watch whatever is on. i too made many changes in my explorations into getting closer to the "heart" of the performances locked up in those innocuous silver discs. while upgrades are "subtle" in one way they are "invaluable" overall.
in spite of the fact that you went from one superb amplifier to one even more competent and spent a good bit of money that you could have spent in more "practical ways", the rewards are immeasurable. the "road" will hopefully also include a much better understanding of good music and a branching out and exploring within genres you like and others you will soon come to like.
Thank you for your response as well as others responses. Its always wonderful to discover new music and we audiophiles forget at times that it was the music that got us hooked into this hobby in the first place. My collection is varied and I continue to look for more artists. Plus, there is nothing like live music. I am going to see Aimee Mann next week in Boston. I came into this world as a rebel and a rocker and plan to continue my life that way.
Many thanks for that great review Pettyfeversk. I had the chance to compare both on the WP Sasha and the XA100.5 was what Sasha's needed. If I had the place for a XA160.5, I would go for. Now there are some ways to improve and use a maximum of their potential : Use of a great preamp and change the initial power cords.
Which preamp do you use? Did you change of power cords?

For me, Pass XA is a very, very great and outstanting musical instrument

Thank you for your response. Here is my preamp situation. I have had the Jeff Rowland Capri for a good while and am thinking about auditioning the Pass XP-20 as I have been told that the synergy between that preamp and the XA series is quite good. I have communicated with some Audiogoners who have mated the Pass XA amps with the Pass XP-20 and they have articulated that it is a fine preamp. I will say that the Rowland Capri is an outstanding preamp. It would be interesting to do an a/b between the Rowland and the Pass. Most people who I have spoken with have experience with either the Rowland Capri or the Pass XP-20 but not both of them.

In terms of power cords, I have Cardas Golden Reference and all of my cabling is Cardas Golden Reference. I am hesitant to change that as when I have done that in the past, I tend to come back to Cardas. Thanks again. Stephen
Hi Pettyfeversk,

I had the possibility to compare my old preamp YBA1 with XP10 and XP20 on the XA100.5. The XP20 is a very fine preamp, but my choice went to a ARC REF5 and I do not regret it. REF5 is far better than XP20, so if you have the possibility to compare both, I think you will be very surprised.
Cardas a very good choice too.
Very nice review.

I have the 30.5 and 100.5's and use Conrad Johnson tube preamps (ART and ACT 2.2) in both systems. With the XA amps having a dominant 3rd order distortion characteristic and my tube pres having a dominant 2nd order, I find a nice balanced sound. I did audition the XP20 and thought it was a great ss pre. If I were to change to ss, it would be at the top of my list.

One of my favorite quotes from Mr. Pass is:

"Anecdotally, it appears that preferences break out roughly into a third of customers liking 2nd
harmonic types, a third liking 3rd harmonic, and the remainder liking neither or both.
Customers have also been known to change their mind over a period of time.
However the issue is partially obscured by the fact that the 3rd harmonic type amplifiers
usually have lower total distortion. Third harmonic usually appears with a negative coefficient,
resulting in what we think of as “compressive” - the example in figure 3. It's worth noting that
odd orders on nonlinearity also can be seen altering the amplitude of the fundamental tone
-something a distortion analyzer doesn't ordinarily display.
The sound of 2nd order type circuits is often praised as “warm” and by comparison 3rd order
type circuits are often noted for “dynamic contrast”. 2nd order type amplifiers seem to do
particularly well with simple musical material, and 3rd order types generally seem to be better
at more complex music."

This might explain why people have different preferences toward sound. Nothing will explain why people "argue" over it though. :-)
I'd second Jpspock's suggestion to try to listen to the ARC Ref 5 (if new, even better, the 5SE). I owned both the X0.2 and XP20 both very nice preamps. The ARC presentation in comparison will be quite a bit different and you may prefer it depending on your musical tastes and listening preferences.
Great review :-)

I have just gone from a XA30,5 to a set of XA100,5. They have not even been burned in (played about 50-70hours) but they are allready mutch better amps than the XA30,5.
I would say that the sound charachter is the same on bouth amps, but the XA100,5 are just mutch better.

I have a set of Avalon Transcendent and the XA100,5 are a perfect match on these speakers......

Thanks for the response. Your new amps will continue to change as they burn in. The biggest changes are in the first one hundred hours and more subtle changes in the second hundred hours. I have about 400 hours on mine at this point.

Thanks for your thoughts. I am giving some thought to the Audio Research Preamps, possibly the LS-27. Can you give me more of a sense why you thought the Audio Research preamps were a better match for the Pass Monoblocks? How does the Audio Research effect your system? What type of loudspeakers do you own? Thanks for your thoughts as it is difficult for me to arrange to hear either the Audio Research or Pass Preamps in person. Stephen
Thank you for an excellent review, very well written and informative. Nice to see someone enjoying their system so much. Thanks again, very helpful to me.

I am glad that you found the review and comparison helpful. Let me know if I can be of further assistance regarding other information or thoughts about the Pass Amps I have owned. You can reach me by cell at 978 877-9123. Take care and have a good day. Stephen

It's your review, and one other members, that is about to cost me quite a chunk of change sir! Grrr...

Thank you for the kind offer, I actually just read your post and picked up the phone to dial your number, then I thought "spare the poor guy" and put the phone back down-for now. Don't be surprised if I give you a ring and blab your ear off sometime in the near future!! ;)


Call me anytime you like, as I hope I can be of assistance as we all take this audio journey. Take care . Stephen
Well I did it. Ordered a set of XA-100.5's! Stephen and Teajay, you two were a HUGE help, thank you!

Thanks for informative review and the comparison of different models along the line.

Can you please elaborate on a comparison to simaudio amps? Did you have the W7M?

Many thanks
Oops, I also meant to include Peterayer as he was also a HUGE help. You three have put up some fantastic and very helpful reviews, Pass owes you one. Now, anyone want to buy a VAC?? ;)

I am excited for you and hope you really enjoy the Pass XA100.5 amps. They are really special and I am sure they will add to your system. What do you have for speakers, a sources, and preamp? Let me know when you will have the opportunity to hear them? Stephen


I had Simaudio Monoblocks many years a go and can't remember what they were called. I know they were about 500 watts per channel and had a coll, very detailed sound. Stephen

I can't wait for them to arrive, should be here in a couple of days now.

I have the following; Usher Be-20's(Danny Richie cross overs), BAT Vk-51SE pre, MBL 1531 CDP, PI Audio Ubberbuss and KCI cables. I'll post up my thoughts after I get a little time with them. Thank you for all the help!


Hope you received your amps and are enjoying them. Stephen
I received them yesterday and couldn't stand it; took the rest of the day and rushed hme to hook them up. My wife and son were there to help and upon firing them up my wife said; "they sound terrible!", had to explain to her(again) they're new, they're cold, give em time. We went out to eat and I left them running, a couple of hours later upon my return.......oh my! Really starting to warm up and sound nice, I listened to them until I had to go to bed, can't wait to get home from work today!

On another note; they are beautiful, the craftmanship is top notch, of course they are Pass so I'd expect nothing less.
Congrats on your new purchase. I've had my 100.5's for 3 yrs now. The best of the ss amps I've heard. Happy listening!

The burn in for the Pass XA100.5 amps that I was told about really worked for me. It was to leave them totally on for 3 days. You don't have to play music. After three days, leave them on during the day and for three nights when yu go to sleep, turn them totally off from the back. This seems to accelerate the burn in. They continue to improve after that but the greatest change was in those first six days. I leave mine in the standby position when not listening and when I power them up, they sound their best when on for 1-2 hours. They just have to warm up to really give you that sound. Let us know how they work with the rest of your system and how you feel about them. Good luck and if you have any questions or I can help in any way, give me a call on my cell. Stephen 978 877-9123 You can call anytime as I turn it off when I call it a night. Take Care.
Great write up. I love my XA 100.5's and my other Pass gear...XP-25, XP-30.

How do you like the XP-30? I should be receiving the XP-20 today and will try it in my system. Have been using the Rowland Capri.
I love the XP-30. It replaced my Mark Levinson 380S which I loved. The XP-20 is pretty close to the sound of the XP-30 from what I have heard. Much better deal buying a lightly used XP-20. I have not compared the two however myself. I was going to audition/buy an XP-20, but before I could, the XP-30 came out and I went that route.
Does anyone who has a virtual system up on Audiogon know when it will be possible to update it. I go to my page and it says I have no system up and I have had one since 2004. I am interested in changing the photos but at this point it is not possible for me to get into my system since they did the change to Audiogon. Stephen

How was the break in period with your Pass XP-30? How long did it take you and what changes do you remember experiencing from the time it was new to fully broken in. Thanks

Thank you for the tips on break in, did exactly as you said and it sounds fantastic!


You've got our interest peaked on that Pass XP-30, please tell us more about your thoughts on it. A mini-reveiw would be wonderful!
Thank you,
Thank yoy Pettyfeversk,just the info i need.
I have the XA30.5 and considering the XA60.5 or 100.5. I extract a lot of juice and the needle swings 70% across often. I do not want to lose the sweetness of the XA30.5. Your notes help indeed.
I am running my Wadia direct and might add a preamp later.(XP20 or XP30 or Krell Phantom).
Great write up and your comments concerning the differences
between the XA series of amplifiers emulates what Pass has
explained to me.

Unfortunately I have a wife who isn't very understanding of
this hobby so I think a pair of XA100.5's are out of the
question for me. I really like that rack that you have the
amps sitting in. Did you buy it or make it ?

Thanks Chuck