<font color='#000000'>Second opinion, I concur with PaulF. I'll even cite specific information. I have several Bryston amps which sport a ground lift switch on the back panel. Indeed, the switch only breaks the chassis ground to audio ground path leaving the chassis still connected to mains ground. This was a problem in my system which required me to STILL use a ground lifting adapter on the AC plug to eliminate hum in my system.</font>