I had the same issue with my EP350.
In my opinion the 'wake up' level is set too high. It requires a high bass input to operate it. For comparison my old Onkyo sub did not have any problem of waking up from standby at a much lower level.
I was not able to listen to EP350 at regular volume level. Especially annoying was to listen at a level when the EP350 kept waking up and falling asleep again:) I ended up with exchanging it for EP500 and I am very happy with my decision.
In my opinion Axiom should re-evaluate this circuit and either lower the threshold, or put a bypass switch, or eliminate this feature completely.
