Buzz on monitor section? 5.1 vs. stereo

I have 5 Genelecs 1031a's on my main speaker outputs. When I have 5.1 selected all is good, however, when I switch to stereo mode on the control surface the center channel and rear surrounds buzz. What's up with that?

I have 5 DynaudioAcustic BM15A and my experience is: I can hear in 5.1 mode the buz from LS and RS and a bit from C. From L and R almost nothing. What can we do? toma from Hungary

RE: Low level hum or buzz in the surround and center channel outputs of the C24: -An early run of units shipped from our factory with non-optimized transformer calibrations. We have modified the testing process to optimize the positioning of the toroidal transformer consequently minimizing any hum. Unfortunately, due to the construction of the C24, none of these issues are field serviceable. We are committed to correcting these issues, and will do so as follows; 1. Make sure that your C24 is registered with Digidesign by mailing in the registration card or sending in a copy of your purchase receipt. 2. Please contact the technical support department of your local Digidesign office. Brent

I had the same problem along with some cosmetic issues. Digi shipped a new unit and paid for the return of the old one. All problems were fixed. This is just another example of the great support I have experienced with this company. Thanks Digi.