Sophia II's and Pass Labs etc

Hce4: thank you very much for that great post. Interesting to hear that you found the XA 30.5 sweeter.

I'm auditioning the XP-20 now.

Spatine,

Kent at Pass Labs mentioned that on my speakers, the XA30.5 and XA60.5 would perform quite similarly with the main difference in power and current. Kent made the point that the XA60.5s would outperform the XA30.5 at high volumes (100db+), while at normal listening levels there would be little difference. Kent mentioned that the XA60.5 are basically monoblock versions of the XA30.5 and were produced for people who desire monoblocks. He strongly thought the XA30.5 would be more than adequate for the Sophia II's, and the XA60.5 would be overkill and not worth the extra money (on my speakers). I should make the point again that those with slightly less efficient speakers would benefit from the XA60.5s.

Kent recommended the XA100.5s over the XA30.5, noting that in addition to power and current delivery, there are other improvements that put these monoblocks in another league sonically and when played at precisely the same volume (important point). At the same volume, sound output, I noticed specific differences between the XA30.5 and XA100.5 which I mentioned in my previous post. He did not elaborate much beyond that, but suffice to say he felt that for the Sophia II's the XA30.5 is a perfect match, the XA60.5s would be a sideways step, and the XA100.5s are the sweetspot in the XA.5 line (he prefered these to the XA160.5 and the XA200.5), so if I had the urge for Pass Lab's best, go for the XA100.5s, but the XA30.5 makes the most sense.

Having said that, I have not compared the XA30.5 to the XA60.5s and I have been told by Mark at Reno HiFi that he does not share Kent's assertion of the XA30.5 compared to the XA60.5s, even on Wilson Sophias. He feels that there is a significant enough sonic improvement between the two that justifies the price, even with efficient speakers. Also, I think I read someplace on the boards that one XA30.5 user found the amp to be inadequate with his Wilson Sophias, so as usual it depends on your situation, system and listening environment.

By any chance has anybody compared the XA100.5 to others in the XA.5 family, specifically for cases that don't have possible power shortage? There is just no way that Pass Labs intentionally designs their mid-level amplifier to be better than the upper 160.5 & 200.5. In fact before the XA.5 line exists, Pass Labs told me all XA's are made the same way, except for power difference. I can see the 100.5 be better than the 60.5 because there can be more to power than the ability to play it loud. But the other way around is a bit hard to believe.

I have only heard the XA100.5 in the XA.5 line. I have read people refering to a "sweet spot" in the various Pass lines. The Aleph 2 in the Aleph line, the XA 160 in the XA line, the X350.5 in the X.5 line, etc. I read somewhere Nelson Pass or one of the employees talking about this. I think they are refering to the price/performance ratio which can be a moving target depending on which generation of amps you're talking about. I don't think it is just more power or stereo vs. mono blocks.

Mark and I too exchanged email's on the differences between XA 60.5 and the XA 30.5 and he conveyed to me they were a worthy upgrade if you can justify the cost and have the floor space.

Also, to enforce Kent's advise, when Stereophile (May 2009) recently reviewed the XA 30.5, the writer was surprised Mr. Pass sent the XA 30.5 rather then the more powerful monoblocks. The review was very positive for the XA 30.5, but the writer felt he would not buy the XA 30.5 himself with the Wilson Sophia II's he owns due to needing more power.

Speakers the reviewer used were NHT Super Zero's and Wilson Sophia 2's.

If you have not read the magazine, here are some snippets.

"Nelson's amplifiers, whether they were his earlier designs for Threshold or his later ones for Pass Labs, have always been on the my wish list, so I was delighted when the opportunity arose to review one of the latest Pass amps. I was a little surprised, however, at Nelson Pass's suggestion that I audition the XA 30.5. I'd expected a pair of X1000.5 monoblocks perhaps,, or maybe the XA 200.5s, fi he thought they'd do the job....but a nominally 30 WPC stereo amp? I double checked, and yes, he did know what speakers and other amplifers I was using, ansd yes, he was aware of the sort of gear I usually reviewed. Despite all that-actually, because of all that-he reiterated his preference that I audition the little guy."

"To be fair, I was running the XA 30.5 well out of it's comfort zone. Nelson Pass explained to me that the front panel meter, which indicates the amount of current being drawn from the wall, "Should sit somewhere in the middle" and "won't move if you running in class-A." During most of my listening sessions, the meter would bounce between the middle and, say, the three-quarters point of its range. When I was listening to and for large dynamic swings, the meter would frequently be pegged. This didn't seem to bother Pass when we discussed it though he did say, "Hmmmmm......so you're pulling a lot of juice." Well maybe if I'd gotten those XA 200.5 monoblocks.."

"Plus in todays high-end audio world, the XA 30.5 is a steal. Compared to what else is out there, a price of $5,500 is low for an amplifier of this quality. No, I probably wouldn't buy one, but only because I think that a larger, more expensive Pass Labs model would work better in my system. Absolutely, positively, and enthusiastically recommended."