You can do this, but you will want to purchase a mic to line level preamp, or a microphone which has a line level output. You will also want to split the microphone so that it hits the left and right channel at once.
Sound will be pretty solid on this, and beware of feedback!
I just got these for one of my clients:
Amazon.com: GTD Audio G-622H 200 Channel UHF Professional Wireless microphone Mic System: Musical Instruments
It is programmed to be able to be routed to any of his 10 different speaker zones in his home at the touch of a button and works pretty well. I still need to get the preamp for it for best results, but it's not bad as it is.
Oh, if the A/V receiver has a 'phono' input with built in preamp, that actually does a pretty good job of bringing mic level up to line level.