My Sony 5ES manual says, if any speaker in set-up (5.1/6.1) is below 8-ohms set amp at 4-ohm setting. I have Energy Audisey 3+2-1's that are 6-ohm speakers and the rest of speakers in system are 8-ohm and amp is set for 4-ohm for best power output. Oh yea, the reason for this is because a lower...