I'm thinking of purchasing 4 ohm speakers.I Currently own an old Kenwood 2 channel receiver rated at 80 watts/channel. I want to buy a receiver for a 5.1 setup under $500, preferable in the $300 range. What kind of power would I need to push the speakers and what receiver. I was thinking of H/K, Denon, or Yamahas. Would my old receiver work teemporarily until I decide?