Very interesting how what you state may relate to dynamic peaks and the need for/benefit of headroom, and how the logarithmic nature of sound perception may give rise to the idea, "You can never have too much power," or does that idea arise mostly because most of us cannot compute how much power we would actually need to propel a given space to a given clean spl?
If you go to some of the amp power calculators you can get a rough estimate as to how much power you need.
It seems that the dynamic peaks of HT in general require more headroom than music due to the dynamic range involved
Try some classical music if you want to experiment with dynamic range. Most popular music has very limited dynamic range around 5-10 and I would peg a good action movie between 10-20 while classical can go to 50db in some instances.
BTW what's up with the power ratings with the Yamahas, the 661 is rated at 90 watts into 7 but S&V finds only 53 watts into 6? The 663 is rated at 95 watts into 7, that suggests the amp is not as powerful as I was led to believe, even in terms of backup or surround duty.
Welcome to the world of misleading numbers. I know somewhere around here Alan has posted the usual amp testing procedures and it is within these procedures that the specs are taken. I believe the procedure is 1 channel driven fully and the others driven at 1/8? to achieve the ratings. S&V run all channels driven to determine the actual output which usually never takes place in regular use.
