<< Ok, that applies to AMPLIFIERS, not surround-sound decoding. >>
There's also a distinct difference between the different amps used in receivers. Cheaper receivers (lower-end Pioneers, Sonys, Kenwoods, etc.) use IC chips for their amplifiers instead of power transistors found in the more premium brands and product lines. Yamaha, for example, uses power transistors even in their cheaper consumer-level receivers, like the HTR line. Power transistors make worlds of difference in the quality of the amplified output. I'm aware that some people can't tell the difference, but to a trained ear they do.
Earlier, it was mentioned that Yamaha receivers are a bit pricey for the power output they have. I beg to differ, because most sub-$500 receivers compared to Yamahas have power output measured in peak (what the amplifiers on the receiver can out maximum, unsustained) ratings. Even the lowest-end Yamahas are measured in RMS (root mean square) power output, which is a rating of continuous power output. RMS is a much more accurate and meaningful rating of power output. Just ask any audiophile; they'll tell you the same thing. For this reason, a lot of higher-end equipment will be measured in RMS ratings.