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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 1 response by elberoth2

elberoth2's avatar
elberoth2
1,223 posts
 
There is a big misunderstanding when it comes to XA series power rating. Pass claims that XA-30.5 delivers 30W in pure class A. And it is true. What they do not tell, and what was shown in Stereophile measurements, is that the amp delivers extra 100W in class AB. So in real world, XA-30.5 is a 130W amp, which HAPPEN to deliver first 30W in a pure class A, not a pure class A 30W amp. Even higher powers are available into lower impedances before clipping: 195Wpc into 4 ohms, and 332W into 2 ohms.

I have not seen the exact numbers for XA-60.5, but my guess is that those numbers double for XA-30.5.

This may explain why Teejay did not have any problems with driving his Maggies, and I do not have any problems with my XA-30.5 driving W/P Sasha.
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