New pioneer vsx-517 keeps going into overload

Fastest way to test is to disconnect all speakers and turn up the vol. If it clips it needs service, then re-connect 8ohm speakers one by one and test until you find the speaker or channel that shorts. Then take that same speaker and hook it up to another channel and test, if it shorts, you know now it is either the speaker or the wire. Now, use a new piece of speaker wire from the same channel that caused it to short, replace the old and test. If it shorts, you've got a problem with the speaker. If your handy with a multimeter, check the resistance at the speaker and you will have your answer. If you are not familliar with a multimeter, just hook up a different speaker where the bad one is and test. It's just process of elimination. Hope this helps