Correct me if I am wrong I should leave the receiver set to 8 ohms as there is 4 qs8s to power also.
Normally you should leave it set to 8ohms. The lower setting just limits the power available to the speakers, but it does appear you are having some sort of problem.
I have noticed quite a few people use seperate amps to power the 4 ohm speakers even though their receivers shold be able to handle 4 ohm loads. Can you explain you decisions? I have been looking at an Emotiva XPA-3 to power the fronts if necessary. I listen to 60% movies 40% music -15db average on receiver average size room.
People have varying opinions on this but Iíve found that my Onkyo 3007 can drive my 3M80s and 6QS8s w/o any problems to much higher SPLs than my ears or neighbors would tolerate. There are some who argue that more power can help but I have no experience in to judge that by.
But I first go into the settings of the receiver check them out and I had forgotten to change the speaker size of the fronts to small after running Audyssey. DOH! Change speaker size to small go back to dragon cave scene at same volume level -15db and everything is fine Denon does not shut down.. Played scene several times infact with no probs at all. So by having the speakers set to large the low frequencies that were supposed to be sent to the subs went to the 4 ohm fronts and that was too much for the Denon to handle causing the circuit protection to kick in. Is this assumption correct?
It does sound like you are correct, however I canít imagine a Denon shutting down that quickly under those circumstances. My experience is that Onkyos shut down easier and I played my for over 2 hours on large w/o a shutdown while playing very rapid beat base heavy GOA trance music. Seems odd.
Is my Denon warranty in jeopardy by running 4ohm speakers and having receiver set to 8 ohms?
I doubt it. But if in doubt you could always just tell them you own M60s.