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
I'm pretty sure that Pass Labs told me that all of their XA.5 and X.5 amps 'double-down', so an XA100.5 would give you 200 watts of Class A into a 4 ohm load... Pretty sure I heard them say that exactly...
Teajay or other 20.1 owners - in your opinion, what is the absolute minimum room width that will work with a Magnepan 20.1?
Stickman, many if not most amps that are touted as doubling down Class A amps actually halve their Class A out-put as they do so. Including Nelson Pass' previous Threshold designs:
http://www.stereophile.com/solidpoweramps/1290thresh/index1.html
For me it's probably a mute point; the XA100.5 is most likely more than I can/would spend even at used prices...
All the more reason to make sure your buying what your expecting. Mind you, the same might be true re: doubling down power/halving Class A bias for the amount of Class A bias in the Class A/AB amps.