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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
teajay
1,655 posts
 
I have had both amps/monoblocks in my system driving my biamped 20's. I loved the 350.5, until I heard the XA-100's and now have the XA-60.5's which sound beautiful in my system. So, pure power/grunt, is not the issue, in my opinion, the 60.5's will have enough juice and still make your 3.6's sing on a higher level then a 350.5. Take a look at my reviews here on the GON for details on all the above mentioned Pass Labs amps. Nelson is a true genius.
stickman451 OP
553 posts
 
Thanks for the feedback. There is a used XA-60.5 on AG right now; very tempting!

It's just difficult to accept that a 60 watt amp can drive the Maggies with more or as much 'power' than a 350.5 but I we talking about different kinds of watts too.
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ghostrider45
449 posts
 
There are not "different kinds of watts" - power, measured in watts, is the product of voltage and current, period. Amps differ in their ability to deliver power across the audio frequency spectrum into loads with complex impedance.

I can see Teajay using the 60.5's in a biamped configuration with the 60.5's on the treble side and another more powerful amp on the bass side to drive his 20's. Music demands far less power in treble than in bass. I'm skeptical that the 60.5 could drive a 20 or a 3.6 full range with satisfactory volume, though.

According to his system page, Teajay is running Threshold SA-1 monos @ 160 watts each on the bass panels and Pass 60.5's on the treble.
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