My REL has recently developed a humming noise. If you remove the LFE connection and leave in the Neutrik connection, it persists. If you remove the Neutrik connection and leave in the LFE connection, it persists. If you remove both connections, it persists. If you remove the power cable it disappears. From what I've read on these very forums, I have a ground loop problem. However, several things bother me; 1. The hum persists no matter what electrical socket I use in the house. 2. The hum persists if I cut the earth wire within the power cable. 3. The hum persists no matter what power cable I use. 4. The hum persists no matter what LFE cable I use. 5. The hum is AMPLIFIED if I touch the Rollover dial. If I remove the plastic dial and touch the exposed metal post, I can make it hum very loudly . 6. If I touch the exposed post and one of the LFE sockets at the same time, the hum is eliminated completely. Is my body acting as earth in this instance? I discovered that by connecting a wire between the earth terminal of my amp and the Rollover dial post, 95% of the hum is eliminated. It only disappears completely when I touch one of the LFE sockets. My guess is the REL has developed an internal PCB fault, through my own stupidity. I recall hearing a humming noise a few days ago when I unhooked the sub from the amp without first powering it down. It was only reconnected for the 1st time yesterday. Any thoughts/comments before I look to having it repaired?