Is the buzzing coming through only the surround sound speakers, or is it also coming though the TV speakers when raising and lower each separately. Is it all the speakers in the surround sound system or is just one speaker? You have to able to troubleshoot and diagnose where the problem is. I found that FR used really cheap speakers in my Work and Play Toy Hauler and if I crank up the volume they sound terrible and or vibrate.
On my Solera the problem was similar - when playing TV or DVD movie sound through house speakers using in-dash Magnadyne as DVD source and as house sound amp. I used Stinger ground loop isolators ( Stinger SGN20 Ground Loop Isolator:Amazon:Electronics) attached to back of TV. I also had to use an isolator on the composite video feed. Result was quite good. Good luck!
2012 Solera "S"
Calif SF Bay Area
I would try it on the audio wires between the DVD player and audio system first. I'm surprised you can have a ground loop with speakers. (They're usually floating, or at least have a common ground.) Maybe that's what the "Noise Filter" part of that thing is doing...killing the low end.