I had my EP350 connected to the sub pre-out on my HK 635 and during idle time it would go into standby mode, get cool to the touch and the LED light would in fact glow red.
I wonder if it has something to do with your amp maybe.

My 600 stays warm continuous and the LED light stays green but after a call to Axiom I was informed that the 600s & 500s will do this due to a completely different type of amp.

Give Axiom a call and see what they think.

Rick
Our Room

smile