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

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.

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.

It is difficult to know whether the X350.5 or the XA60.5 would be better for you. It depends upon the size of your room, the music you like, and the loudness level. For example, classical music requires alot of power to avoid becoming congested and strained.

There is no doubt the XA.5 is better than the X.5, by a huge margin. However, you may need to consider the XA100.5 (or even the XA160.5) for the 86db load into 4 ohms.

Personally, I would be skeptical that the XA60.5 would do the job. You can arrange a demo from Reno Hifi if you first want to try. Ideally, the XA160.5 would probably be the pick.

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.