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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
rtn1
535 posts
 
There is a big difference in the sound of 'Class A' between the XA.5 and the X.5. They are entirely different amps despite their similar cosmetics.

Buy the X.5 because it is a good deal and a value component. Don't buy it because you think the Class A sound is equivalent.

In the end, both are great amps.
unsound
7,313 posts
 
Stickman, are you sure that the XA 100.5 maintains Class A bias (or something to that effect, as there has been discussion here on the technical classification as to whether Class A/AB and Class AB amps technically deliver any Class A bias(?))or is the Class A Bias reduced and the Class AB increased as it doubles down?
stickman451 OP
553 posts
 
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...
stickman451 OP
553 posts
 
Teajay or other 20.1 owners - in your opinion, what is the absolute minimum room width that will work with a Magnepan 20.1?
unsound
7,313 posts
 
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
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