Dear users, I recently set up my Denon AVR1802 amp with a REL Strata ii subwoofer. I have had this set up running before previously in another house. This time round, I noticed a background hum from the sub when the amplifier was in standby or on mode. After disconnecting everything, I turned the amp on and measured the case to earth voltage (The AVR1802 is double insulated and earth free). I measured a voltage of about 117V ac to earth. I've opened the amp and dis a visual to see if something had fallen in and was shorting anything to the case but I could not find anything. Since then I have bought a Marantx SR4400 which is performing well. However, I can still measure a standing voltage of about 80Vac to earrth when nothng is connected. When I connect the REL to the amp, the system gets an earth path from the REL via the subwoofer coax cable. My concern is, should there be such a high voltage in the first place on the amplifier case?