I am sorry to say this but, if there is a problem in your system with 3 different subs (out of 3), I would be looking at your system and/or house wiring. I do not believe that SVS is perfect but it is hard to think that they could stay in business if this was typical of their quality control.
They recently sent me the three I have now (2 x SB3000 and 1 x SB2000Pro) and all three are silent. The noise I referred to earlier was the fault of an XLR-to-RCA adapter that I had on the SB2000Pro but it disappeared with a change of that adapter.
I hope you find something compatible.
Thanks for the reply. It wasn't 3 out of 3, the 2000 was silent, it's only the 3000 that was faulty so i'm guessing if the 2000 was running as it should my house wiring is fine.