Hi snazzed,
I just wanted to add the importance of having available dynamic headroom. Virtually all receivers and even many separates that use a switching power supply have no dynamic headroom. The power supply is sized to the RMS continuous power rating of the amplifier. In music and movies it is the dynamic peaks being clipped or compressed that cause the loss of performance at higher levels, which can be reached very quickly in large rooms. A few numbers to consider which Bridgman has already touched on; every time you double the distance from your speakers you lose 6dB, dynamic peaks can reach 12dB or more in music and movies, but you only gain 3dB for every doubling of the wattage of the amplifier. You can see how quickly you need a lot more power. A linear power supply with lots of storage capacitance will allow the amplifier to produce multiples of its rated power for short periods of time. All of our ADA amplifiers have this capability. So my suggestion would be to get a receiver that has pre-outs and not worry too much about its rated RMS power. Then get a separate amplifier with lots of dynamic headroom to power the front three channels. You can power the surrounds either from the receiver, by adding more channels to your main amplifier that is running your fronts, or by getting a smaller multi-channel separate amplifier to power the surrounds. There is a lot less dynamic power required for the surround channels.
