Oh no!! I've just returned from London all excited with my Boogie 400+ only to find it has a problem. I am really annoyed about this as when I tried it out in London (fairly extensively) it was fine. When I set it up in the studio it started making a really horrible humming noise centered around the 50 hz (uk mains) frequency. I tried revalving it with the new set that I got with the amp but that did'nt make a difference. With the amp in standby I can hear the hum originating in the power supply. My friend seems to think its one of the capacitors that has gone funny. Does anyone know how to fix this problem or has anyone else with a 400+ or similar had the same thing happen?