How many watts per channel are enough?

Thanks, Wilson667. It should be noted that the Crown calculator applies to one speaker, not two. The results it gives are consistent with the calculations I provided above when extrapolated to two speakers, and assuming 0 db headroom.

I would not count on headroom specs, if provided for the particular amplifier, to be either meaningful or helpful. The amount of time that the specified headroom can be sustained for is not usually indicated, and can be expected to vary widely depending on the particular manufacturer's approach to "specmanship." Also, sound quality may degrade significantly at power levels in that region, to a greater or lesser extent depending on the particular design.

Regards,
-- Al

I want to thank everyone very much. I decided to give the Prima Luna a try. I have a 14-day audition period. I am purchasing it from Kevin at Upscale Audio, who based on my due diligence has an excellent reputation. He would be surprised if the 34 watts are not sufficient.

The Prima Luna website explains, "if two amps are . . . both . . . using a pair of KT88 tubes per channel, how can one be rated at 40 watts per channel, the other at 80 watts per channel? This is a simple engineering and math question, and these are the two possible answers:

The higher powered amp isn't really meeting it's specified power rating and/or the tubes are being run very hard to get that extra power. . . .

The benefit of doubling power from 40 watts to 80 watts will only increase maximum volume levels by approximately 3dB."

That makes a lot of sense.

You are tapping the amp out on musical peaks. Most tube amps have distortion climbing when tapped out and bandwidth narrowing. The distortion many times sounds like congestion. Remember, double your power and you only get 3db. Also, check to see if 34 watts is 34 watts. If at full power you have good square waves, distortion less than1% and bandwidth the range the of speakers then you will get an idea what you will need. I think you need at least 100 wpc of power. Jallen

Dymani28,

"Hey, follow K.I.S.S. (keep it simple, stupid), the general rule of thumb is to use double the required RMS output, fuse or breaker protect the speakers, and listen for audible distortion. This setup can even be used to lower THD. If you have 8 Ohm speakers and a 4 Ohm amp you can cut THD in half while maintaining proper power output. I, for instance, use 12 ohm speakers L/C/R/SR/SL on a 8 ohm amp. This technique works wonders for sound quality while maintaining volume levels."

Regarding your post, I have to ask, are you serious or just kidding around. I really don't mean to offend in any way if you are being serious, I just don't think I fully get what you are trying to say here. You use your system for an example. Can you list your components? I do find the post very interesting. Its possible that I'm just not reading it correctly. And like I said before, I'm not at all trying to offend you, even if we end up disagreeing on some things.

FWIW:
http://www.ftc.gov/opa/2000/12/amprule.shtm