Originally Posted by gemma-the-husky:
“re the sound output.
40w per channel is going to be enormously loud into any normal speaker. You won't listen at that level, hardly ever, I expect. That is why the spec of 1000w is immaterial
however, action movies will have explosive spikes of noise requiring an amp capable of delivering substantial peaks without clipping for short bursts, and speakers that can handle occasional high levels of input without distortion. that's what the better reviews test, I think.
the connections can be important for an amp. ideally you want to put assorted sources into the amp, and a single output to the TV, so that you can switch everything (sound and picture) instantly, with a single switch.
You may also need pass through facilities, so you can watch the TV through the amp without the amp being on. They don't all do that.”
This is the reason why a more powerful amp could be useful.
As a purely hypothetical example....
Say you have an amp rated @ 15w output. If your normal listening level is @ 10w from the amp that leaves @ 5w "head room" before distortion may occur. So if in a film, or a CD, there is suddenly a very loud passage that equates to an output of 16w on the amp then the listener is very likely to hear that peak as distortion.
With an amp rated at 20w the 16w peak would still sound loud, but because the amp has the capacity to output 20w the 16w peak is still below the limit for the amp.
Now that is a very simple explanation and ignores a number of factors but it does show the principle.
For choosing an amp the RMS level hidden away in the Technical Specifications at the back of the owner's manual is often the best guide of the output power of the amp. It isn't perfect for a number of reasons but it will give a better idea of the true output performance of the amp.