Pass labs XA60.5 anything wrong with them.

I had some different model Pass amps and I thought the power rating was very conservative. I had the Aleph 0 rated at 40 watts/ch. It was a while ago, but it had no problem driving my B&W 802 s3's in a medium size room at fairly high volumes. At the time, I was interested in a Krell KAV 250 and had that in my system, as well. That was a nice amp too, but I ended up keeping the Pass. Power wasn't an issue.

I see, but imo, 89db sensitivity should be the cutoff point. Anything lower is taking a bit of a chance, imo. As for me, I'm looking at a pair of First Watts F4s in bridged balanced XLR mono operation. You have 100Wpc into 8 Ohms. However, you need a preamp with at least 14db of gain. And you need efficient speakers. My speakers are 94db sensitive, so no problem really. It's an interesting amp to say the least, and hand built by Nelson Pass!

07-11-13: Tonywinsc
60 Watts is a lot of power even for speakers not so efficient. Lets say you have a speaker that outputs 89dB at 1Watt/1meter. That results in an SPL of 97dB at 3 meters with 64Watts. That is pretty loud unless your goal is permanent hearing loss. 100dB is standing next to a pneumatic jackhammer, for example. I guess the question is does a class A amp still sound as good at maximum output as it does at 1 Watt.

This analysis does not take into account the dynamic range of the music, however, meaning the DIFFERENCE in volume between the loudest notes and the softest notes. Well engineered minimally compressed classical symphonic music, for example, can easily have a dynamic range of 30 db or more, and a few such recordings in my collection even exceed 50 db.

A dynamic range of 30 db means that 1000 times as much power will be required for the loudest notes as for the softest notes. 50 db means that 100000 times as much power will be required for the loudest notes as for the softest notes.

On many such recordings, I find that brief peaks reach 100 to 105 db at my listening position, although average levels may be in the 70's or even less. Due to their brevity, and the moderate average level, those peaks do not represent a threat to one's hearing.

On the other hand, many and probably most rock and popular recordings these days are compressed to a dynamic range that is in the single digits, meaning that less than 10 times as much power is required for the loudest notes as for the softest notes. Your conclusion would certainly be applicable in those cases, IMO.

One minor additional point: In your example, since two speakers are being driven the 97 db figure is likely to be around 100 db, and possibly as much as 103 db.

Regards,
-- Al

Thanks for that info. I agree 100 percent. :D

For sure, total dynamic range must be considered. If you have your stereo volume set for the quietest passages to be at 40dB or so, just above the average room background level, then you have 57dB of headroom (considering 97dB max). Of course, I typically have my volume set at a point where record background noise is just audible on my quietest records at the lead in groove. I think that gives me somewhere around 40-50dB of headroom which can get pretty loud, and then my wife makes me turn it down. In general, speakers have a linear output of SPL (in dB) vs. power up to around 100-105dB- some less, some more. That is a generalized statment- better to consult your owners manual for more accurate specs. What that means is you can pump more power into the speakers but they will not get much louder. Some of that extra power will just turn into smoke:)