Erik, welcome. The first point is that the 3808 can't actually bi-amp speakers, despite the suggestion in the manual. There's only one power supply section, and doing the so-called "bi-amp" procedure can't increase the power available in any amount.
Although you use the term "clipping", it appears that you're instead talking about overheating and shutting down. The volume setting that you mention seems to be a bit high for average use. Do you have an SPL meter to measure the actual sound levels when this is going on? It may simply be that you're listening at too loud a level, which the overheats and endangers the receiver, and much more importantly endangers your hearing.
One additional thought is that sometimes a loose strand of speaker wire can be vibrated into contact at loud levels and cause a shutdown even if overheating hasn't occurred. Very carefully reconnect all the speaker wiring, even if it appears to be okay.
