It's fine, the red does indeed mean no signal. In other words, the receiver only sends audio to the sub when it is below 80hz (or whatever your crossover is set at). The red means the sub is on, but hasn't received any signal to actually put it into an active mode. Once the below 80hz sounds start coming through, the sub kicks in and the light turns to green. It will stay green for a little while even if the lower sounds stop coming (not sure what that time amount is). My sub is the VTF-2, but it works this way. I would assume the Axiom sub is the same as far as this goes.
