I recently bought the Wharfedale Diamond 8 cinema package for 100% HT use. The Diamonds are have a sensitivity rating of 86db and impedance of 6 ohm, so that means they are power demanding speakers. My question is should I get the HK AVR 320 which is rated 55x5 all channel driven or the AVR 510 rated 70x5? Would I be missing a lot of features if I buy the AVR 510 since it is an older model. Isn't logic 7 same as Pro logic II? I live in an apartment and my living area is 16x20. I like to listen loud but not loud enough to break my lease. Pls help me decide.