I purchased one sub and the manual says that the rear led is red in standby and should turn green when the sub is on.Im mine , instead of the led turnning green, it remains red even when itn is on. the only light that changes is the front led turs blue when the sub receives signal.the sub is working properly, but is turning off automatically?Is there any problem or this is a manual error? It is still under warranty , so i can exchange it is this a malfunction?does any body has opinion about this sub? Thank you for any help