Marantz AV7701

I am experiencing horrible humm issues with my 7701 setup.
7701 is connected via XLR to 5 mono amps. Combination of Bryston and Wyred.
The 7701 when connected creates a humm noise independently of volume. The higher the amp gain and speaker sensitivity the higher the noise. I have a suspicion there is some wrong with grounding or what have you?
All units are powered and grounded via a BELKIN Power Unit.
Any ideas? I am ready to ship the 7701 back but wanted to get your input maybe i'm missing something...
I am running my AV 7701 with a Parasound 1206 and experiencing the same Hum/Buzz that others are talking about. My friend bought a 7701 and connected it to an older Adcom amp and also experiencing terrible hum worse than mine. I bought a Theta Intrepid and am going to test it with that Amp and will report back. I am wondering if all 7701's have this issue if you do not use the matching Marantz amp? This is bad news.
I contacted Marantz USA Support today and explained the hum situation. I informed the rep about the various online forums where numerous consumers are experiencing this same issue. He casually said that "many pre-pros have hum". He recommended that I buy a device called a "Hum- X". I said "so basically if consumers don't buy your matching amps, they will experience hum?". This seems to be the case. "So now I have to spend money to buy an ancillary 3rd party filter to fix what seems to be a Marantz design flaw?"

Well, this also seems to be the case. I ordered a hum-x via Amazon Prime for $59.00. What I like is that it installs inline with my Power Cord instead of being in the signal path via XLR's or RCA's. I will let everyone know in 3 days if the Hum-X cures the hum. This is disappointing and Marantz should fix the issue but if a $60 item will make the issue go away, this is still currently one of the best pre-pros for the money for sure.
I purchased am AV7701 for a number of reasons. The AV7701 was exhibiting a high level of hum when I put it in the same configuration as my Integra DTC 9.8 which was dead quiet. I reduced the hum to close to zero by using the RCA interconnects in place of the balanced interconnects. The hum is still there, but it is truly faint and you actually do not notice it in practice.