Originally Posted by cavu
The short answer is no.
You can achieve THX standard loudness with 80+W/ch and speakers that are 86+dBSPL efficient.
*Most* AVRs and HT speakers meet those requirements!
I don't come up with those numbers. Assume speakers with 90 dB sensitivity. Assume 2 meters average listening distance to speakers. 6 dB loss for 2 meters of distance. I figure you need 128 Watts to hit 105 dB.
Of course, you don't that continuously. But I have my doubts that many receivers can supply the needed power.
I am not sure most receivers can manage 80 Watts / channel. Take your average $500 receiver with a 400 Watt power consumption rating. I figure maybe they can do 25x7 Watts continuous at 1% THD. Maybe they can hit peaks of 60x7 Watts. On loud action scenes in movies, I suspect they simply can't provide sufficient power.
Of course it would be great to have facts. For example, to see where peaks on each channel are occuring, how close together they are, how much power the filter caps can supply for these peaks, etc. I know of no source for this info. I imagine THX has a pretty good idea. If they are honest, maybe there's some hope, because some pretty midrange models have managed select certification. I would like to see what sensitivity speakers you are supposed to pair your receiver with, and at what listening distances, because that makes a big difference in terms of how much power is needed.
My Yamaha RX-Z7 does not sound good at reference level, and it's 2nd to Yamaha's top of the line. I will accept the argument that some company's models produce more power, but I still have my doubts that most receivers perform well at reference level.
Also, I think your powered sub needs to keep up, or you really can't claim the ability to play at reference level.
If I am right, the good news is a slight reduction in SPL gets you to power levels most receivers should be able to handle. So what if you can only hit 100 dB peaks. I think that's sufficient for many people.