Help with Buzzing in Speakers

I have a Chiro 800 and C5.1 processor in my HT set up, when I turn on the units I get a low buzz,not hum through the speakers when I am in the 5.1 mode on the preamp, the buzzing disappears when the movie turns on. The buzz is not present when in stereo bypass for CDs, only in 5.1 mode. Is there any way to eliminate this buzz? I would appreciate any and all suggestions. Thank you. Rick
This is an educated guess, as I don't know what kind of cables you're using or if any line conditioners in the set-up. On DVD's (I'm presuming that is your HT source?)there is no recorded audio in the "menu" set up between those "sound effects" they use (and that is usually 2 channel NOT 5.1) What it sounds like you have is noise from your processor when no audio signal is present. This could be your processor chip or some other "garbage" present in your digital signal, probably from the transport end. Since it is not present when in bypass or when a digital signal is detected, the root of the problem would suggest either the processor but more likely (a guess) the transport (are you using the Chiro's D/A or do you use external D/A when NOT using it for 5.1?). Obviously some troubleshooting needs to occur but that's where I'd start (esp. if you have good cables, for RF rejection and line conditioners).
Let me add this:1. You may want to try moving the player further away from the processor. 2) try a different wall plug for one of the two involved components. 3) Check to make sure you don't have a "rat's nest" with your cables. 4) Try a different digital cable (are you using F.O. or coax?) 5) Refrain from cursing if this doesn't work - haha - Good luck and hope one of these suggestions works!
Treyhoss thanks a bunch I will troubleshoot with your suggestions. To add info for you I have a DVD 05 and a Muse 2 dac. The buzzing was occurring before I added the dac so I don't think its the dac, I think it is the 800 processor. I reset the 800 to factory default setting and the buzz dissappeared but after about 4 hours it came back, sounds like a warm up problem with the 800 you think? I use a panamax 1000+ line conditioner/surge protector, any thing I can check to see if it is the problem. Thanks again for all your help. Rick.
It does sound like a thermal problem. Try putting the processor on tip toes and don't put anything on top of it. The tip toes will not only provide improved stability but will allow for better air circulation around the unit. I use these on my amps, processor(s) and transport. You should only require 3 of them set up in a triangular configuration to create a plane. If that doesn't work then send the unit back if it's still under warranty. I know the latter is a pain but.... If it isn't under warranty, try opening the cover and carefully, using compressed air(from a distance), blow out the circuit board. You may have some dust in there although this would be a last resort. Good luck.