If your receiver has an FM coaxial plug on it, you could run a coaxial off of it and then wire the ground in many different ways from that.
I would second that whenever I run a new amp I run a ground cable back to the receiver as well and don't have problems with hum.
I recently added an inuke 6000 DSP driving two UXL-18's. I was going to modify the fans, but after seeing many members with airflow issues, I decided to put it in a mechanical closet about 30' from the receiver. I purchased a Blue Jeans Cable sub cable and ran the two speaker cables, the ground cable and a 12 volt trigger switch back to the receiver.
I use coax cable for just about everything including the ground cables. I have a "block" with 8 coax connections that I plug everything back into near my receiver and ground it all to the same outlet ground.
All hum that I had is gone, other than when I switch everything on, I get an audible hum out of the UXL subs prior to the receiver locking in the HDMI input. Once the handshake is made and it clicks all hum is gone.
I also use to get hum in my mains as I have them on an active crossover. Grounding everything together fixed this issue, though I do still get a hiss, but I believe that is amp related and the fact that the compression drivers are over 100 db efficient.
Good luck, hum sucks.