Do they calculate their watts per channel different than what other brands do? It just seems like their watts per channel is lower, but they seem to have more than enough power to run most setups. Or is it just that other brands list higher watts per channel that what they really have?

Quoting DigitalGhost:

Quote:
They use "real" watt. They calculate their watt how much watt they can produce continuously with all channels in use. Some other brands calculate the watt how much watt they can produce for a short time with only one channel in use.

Exactly what i would say. That's often a probleme with cheap manufacturers. They write a big Watt-number on the package (1000 Wmax, ...), but this means nothing.

The only thing you can compare is the W rms. This can give you a approximate comparison of the power of an amplifier, even if this also depends on what impedence you run the amplifier and to what maximal %THD (don't know the english word, in German it's called "Klirr") it's measured.

So don't look after the Power of an amplifier, but take one with a "name" and hear it before buying.

Searched something in the web which could explain it a little bit more detailed. Didn't find something good in English, just German.

Not the best, but Ok:
http://hometheater.about.com/cs/audiocomponents/a/aapowermada.htm

More power is always good, but remember to get 1db more Loudness you have to double up the power.

Harman Kardon typically uses high current designs which allow their products a considerable amount of headroom for short term peaks. Headroom, is a reference to the difference between the RMS (or in some cases the average) power rating and the peak power that can be delivered in a short term burst. For anything but a monotone spoken recording there can be large differences between the highest and lowest sound in a recording (referred to as dynamic range). An amplifier with 0 headroom would only be able to deliver peaks slightly above the RMS or average rated power which would mean that you could only have peak sounds at that maximum level with the average being much lower (unless you don't mind considerable distortion and severe compression of the source's dynamic range). For an amplifier with a good deal of headroom it may be possible to deliver short term peaks up to 2 1/2 times the RMS power ratings or more. With this "extra" room for the short term louder peak sounds the amplifier can be run with the average level closer to it's RMS rating thereby resulting in greater overall volume. Unfortunately headroom is not a specification that all manufacturer's provide (especially when it is less than impressive).