I received my new EP350 last week and also noticed that the LED always stayed green when I shut down my system. I emailed Axiom about the power LED being green and the sub always being warm, thinking maybe it was never switching to standby. The reply from Axiom said "The light on the subwoofers amplifier does remain green when in the standby
position. The current draw when idle is equivalent to that of a night light."
One of my sons also has an EP350, it is a year or two old, and his led does turn red in standby. I also notice the online PDF of the EP350 quick setup guide says the led will turn red in standby, but the same guide that ships with the sub only says the led is green when on and yellow for fault condition (says nothing about red-standby). So I'm thinking there has been an engineering change in the last year or so with the EP350. Either way I feel sure it will not harm the sub to leave it turned on. As always I will unplug all my electronics (including sub) if I will be gone for an extended time.
Bill
