te1221 I think the way the 4 and 6 ohm settings work is.. 4 ohm speakers make the amp get hotter faster, so when you set it to 4 ohm mode, all the amp does is lower the current output to protect itself from overheating. So dynamics might not be as good and maximum volume will be lower I think. that's why it doesn't get as hot. so it's recommended to use 6 ohm mode
Here is another controversial tip for you.. I've been back and forth on both sides of this argument myself.
People say if you bi-wire the sound gets better. That it's due to a flaw in the design of the banana ports.. they use some kind of internal bridge instead of the more common metal bar that connects both speaker taps on the outside of the speaker box. So disabling the bridge and connecting 4 speaker wires per speaker supposedly improves the sound. Also if you have two amps obviously it provides more power. But the first argument about a flaw in the internal bridging is the one I believe now. My receiver does up to 7.1 so it has a bi-amp mode where you can use the height channels and the front channels both for the front two speakers in bi-amp mode, but I guess the receivers amp is just one module so all the power comes from the same place so it doesn't really give you more current to the speakers. Anyway I'm doing it and it does seem subtly better in the treble.
Also if you have an onkyo receiver, use audyssey in music mode not movie mode.. apparently movie mode rolls off the treble and music mode is flat
Gear list: Main setup - Kef Q900, Svs sb12-nsd subwoofer, onkyo 609 receiver, epson 8350 projector, elitescreens sable 92" screen, mac mini htpc
bedroom setup: PSB Image B5, maverick tubemagic a1 amplifier, hifimediy sabre9023 dac, ZMF Fostex T50RP modded headphones
preordered gear: Light Harmonic Geek Pulse X dac and headphone amp