NAD T973 Power Amp - Power Rating 7x145w or 2x200w

Eandylee, mostly MCH amps in a single chassis using a single, large powersupply do the exact same thing. The available juice is shared between all of the channels. The idea is in home theather you rarely need all channels driven.

Most seem to design around the assumption that during peak demands (read helicopters, car chases, and explosions) most often only three channels are being driven to the max, the others are mostly idle. It can be any of the three channels, it doesn't really matter.

That way you have a bunch of shared juice on tap without having to overdesign the amp (separate large PSU for each channel, etc). This issue to cost and space savings. else you would just buy 5-7 Krell FPB monoblocs each in its own chassis.

Power ratings are sort of a funny business. Everyone rates them differently. And everyone interprets them differently. Maybe you would be better off comparing VA ratings of power supplies instead? That might give you a better picture of how much balls the amp has. Just a thought.

Thanks guys! very helpful.

Here is another multi-channel amp with similar spec, but it looks like it's not as good(effective) as NAD I guess

POWER OUTPUT (Anthem PVA 7)
# of Channels Driven --------- 1 ----- all(7) -------
Power rating ----------------- 125 --- 100 -------

http://www.anthemav.com/NewSitev2.0/AnthemProduct/PVASeries/PVASpecs/PVASeriesSpecs.html

It means
when listening to movie(5 or 7 channels) = 100W/ch
and when listening to music(2 channels) = little less than 125W/ch.

Only 25% increase, compare to 40% increase for NAD for 2 channel applicaton.

So, whatever their design method, I geuss that NAD amp is better deal in terms of 2 channel application?

I thought it's very natural to provide the 2 channel only power rating, but surprisingly not many provide it like NAD and Anthem.

NAD is known to be very conservative and honest in their power ratings, and I guess it fits my need well, so I'll probably get it after reading some more reveiws and auditioning.

Better deal, depends. Not all watts sound alike.

Eandylee - I agree with Aroc. Don't be so quick to judge an amp based strictly on power ratings - there is much more to an amp than power. Though the NAD power supply is capable of more continuous power the Anthem amp still has plenty, as well as excellent write-ups regarding sound quality. I would look very closely at it, and listen to both.

Indeed, be careful, because there's more to amp design than watts. NAD is a very good company, and what I had before I bought my first high end amp. This amp had less power but sounded much better for music. Still, I think NAD is a fine choice. Just remember that 200 watts is not 40% louder than 140 watts. You would need to double the power to hear a perceptible 3db difference. Our ears perceive volume exponentially. For most speakers, the first watt gets a huge amount of volume- about 90db, depending on the speaker's sensitivity. This is the volume, in decibels, produced with one watt of power measured one meter away. Because you only add 3 db for each doubling of power, the second watt produces 93db, the 4th watt 96db, 8 watts 99db, 16 watts 102db...... A chain saw produces about 107 db, so you'd need less than 64 watts to get chain saw loud. As you can see, it is getting more and more expensive to get 3db louder, and the difference between 140 watts and 200 maybe like the difference between the top speeds of a ferrari and a porshe- You might drive that fast until the cop arrests you, or play it that loud before the neighbor bangs on the door once. If you buy your speakers with sensitivity in mind, you will much more economically get ear crushing volume, if that's what you are after. We all get the feeling that you want good sound as well, so don't turn up your nose at what may be a better sounding amp for a 60 watt difference you may not need....Best way, if you are buying new, is to take them BOTH home and listen 2 channel. Play some piano at moderate levels, play a DVD, but audition them with the same source and speakers.