Pass Labs XA30.5 and ModWright KWA150

Because of their power ratings, these amplifiers cannot really be compared apples-to-apples. I believe if you compared them on speakers that can be well driven by the XA-30.5, the superiority of the Pass Labs would be clear.

The XA-30.5 is really in a class of its own...as much as I respect the work of Modwright.

I am looking for a neutral and detailed account of differences in sonic flavor using various kinds of music.
Ral (Threads | Answers)

There are plenty of reviews of these amps. I will say this about the XA-30.5. It has no sonic flavor. It amplifies what's fed to it without embellishment. To me, what makes the amp unique among solid state amps is it's grain free treble and midrange, combined with it's total bass grip and resolution.

Here's what I suggest if you really want a satisfying answer to your question. Buy a used KWA150, and contact Reno HiFi to obtain a demo XA-30.5.

Listen to them both in your system...assuming you have the appropriate speakers for the XA-30.5.

Keep the one that you prefer.

So designer of OTL amp believes that output transformer is BAD (for his varous reasons) and did everything he could to create...OTL (OutputTransferLess) amp and you saying basically to him - you did huge job to eliminate output transformer but I will install it into the signal path ANYWAY and destroy your intention and your goal...and your sound.

Michael_moskowich (Threads | Answers)

I have owned Atma-Sphere amps on and off, and I have had some extensive email discussions with Ralph. For exactly the reason Michael_moskowich highlighted, the issue of using ZeroFormers with OTL amplifiers has always struck me as being counterproductive to the goal.

Like Zybar, I have also tried Atma-Sphere amps with and without ZeroFormers. The amps were M-60 monos and the speakers were Silverline Sonata III. Unlike Zybar, I did not find the improvement with the Zero/M-60 combo to be preferable to an entirely different amp (which happened to be a solid state model). The differences were substantial. I also tried the ZeroFormers with the solid state amps as an experiment, and I still preferred the system without the Zeros.

ZeroFormers are something that are system and listener dependent, IMO, which makes the Speltz home trial offer valuable.