anybody everheard a sub make a low hum when idle (all components off) . the signal led stays green all the time it never shuts off.(red means off or standbuy correct?) maybe i dont have it connected properly? i have two subs in this setup one wired to the lfe out of my denon 2802 and the other is wired to the front r&l outputs of receiver to high level inputs on sub. i tried connecting both subs to the receiver lfe preout with y splitter to both low inputs on subs but had very weak sub response. any suggestions? ps. the one that makes noise is the sub thats connected high level.