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Pass Labs A/B amps vs Class A amp and Actual Power

Dumb question; how can you compare the actual power or ability of an amp to drive a tough load (such as a Magnepan) when looking at a Pass Labs A/B design such as the X250.5 or X350.5 vs one of the full class A amps like the XA60.5 and XA100.5? For example, which amps would (from a standpoint of just pure power/grunt) drive 3.6's better, an X350.5 or a XA60.5?
stickman451

Showing 2 responses by peterayer

peterayer
1,382 posts
 
I just bought a new speaker which is a very demanding load - 87dB, 4 ohms, sealed enclosure. I first heard it with the XA30.5. It sounded OK. My XA100.5 made it sound much better, but still a bit closed-in during complex passages. I traded in the XA100.5 for the XA160.5 and what an improvement! Open, nuanced, dynamic and effortless. I don't understand it, but the control is better, scale and staging are better and ultimately, I'm more involved with the music.

I would buy the largest XA.5 amp you can afford. If it is not large enough, try the X350.5. Contact Reno HiFi for an in-home audition.
peterayer
1,382 posts
 
I forgot to mention on my last post to this thread that another big difference between the XA100.5 and the XA160.5 is the amount of current that they can each deliver - 8 amps (I think) vs. 36 amps. I can't begin to understand why this makes such a difference, but it does. There is much less strain, particularly at loud volumes, with the added current. Demanding passages on demanding loads just sound more open and less compressed. There is a sense of freedom and effortlessness with the XA160.5 that is astonishing.

Perhaps someone with more technical knowledge can talk about what the increased current actually does.
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