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

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.

As Elberoth sugggests, the XA.5 series is very conservatively rated, I can tell you that having owned the XA30.5 I would discuss it with Pass Labs, if they tell you it should be no problem, you can trust them.

I actually gave Pass Labs a call today and they were very patient and helpful in discussing the relative power(s) of their amps. They recommended either the XA100.5 or the X350.5. They felt that in my larger room and considering my history in using Horn speakers (In addition to the 3.6's I have a pair of Klipschorns) that the XA60.5 might not quite get the job done for me. All their amps 'double-down' into 4 ohms so I would have either 200 watts of pure Class A (that's a lot!) or 700 Watts of Class A/B (that's a lot too!)... And, even with the X350.5 I would get 80 Watts of Class A performance before it slipped into A/B mode; sounds like the X350.5 is a good deal and just the ticket!