After several months I had some time and finally got all my cables to move both subs to the corner and connect a BFD. The subs are a Paradigm Servo 15a and a Von Schweikert S/3.I am using Cat sub cables.The BFD is connected between the Ref 30 and the subs.I am using Monster audio cable from a Y from the sub out to channel 1 and 2 on the BFD. The BFD is plugged in to a Vansevers Model 85 line conditioner with a cheater plug.When I was adjusting levels on the the BFD I heard a loud hum from the VS sub the Servo was fine so I started to trouble shoot.I changed the cables and inspected them, put a cheater plug on the VS sub, switched cables from the Servo to the VS still a hum.After an hour I took the BFD out of the path and connected the subs to the Y from the Ref 30. Guess what? No hum!BFD gurus what could be the problem? After spending a couple hundred on the cables and the BFD I would like to EQ the subs. Anybody possibly have an answer to this problem? Thanks, Steve M.