can i pass rear out to main input on hk avr20ii

i'm using a seperate amp for main channels, so my main amp in the receiver is not being used. would there be a problem with passing the rear out to the main in? main amp is 50wpc and the rear amp is 20wpc.
I don't see a problem with the rear pre-out to the front main in as you are thinking. Don't forget to change the speaker cables also.

well i made the switch. rear volume was way louder, had to turn it down to 70 from 96 or max (100). problem was i picked up a loud hiss that did not increase with volume and pops when i operated the remote (volume control). i could hear the hiss from where i was sitting so it was unaccatable. i don't know what to make of it. i quickly switched back. it is dolby pro-logic if that makes a difference.
Oh? Do all channels have main-in/pre-outs? A few years ago I had an Onkyo receiver...I recall doing this and it worked fine. Once the amps are freed from their respective pre-amp outs...jumpers removed, it should work fine.

The rear pre section should not care which amps it is feeding to my way of thinking. Also, maybe you have a bad cable?

there is only one main-in. the pre-out is not bridged to an input. i will try a dirrerent cable and a different movie.
My Onkyo had pre-out/main-in for all channels (jumper pins). Once you removed the jumpers the split was complete...I am thinking this is your problem.