I had the same problem with different components, but the fix was the same. I put a cheater plug on my preamp and my system has not had any hum problems since.
Audible Hum
I just hooked up a pair of Clayton M70 monoblocks to my Martin Logan Requests. There is now an audible hum coming from the speakers when the volume is off. The amps are located close to the speakers.Is this the problem? I am new at this and would like the groups help. I did not have this problem with my B&K amp which I replaced.