I received my new LFM-1 EX sub last week and finally hooked it up on Saturday. At that time I did not notice anything odd, however on Sunday I noticed a slight hum when I was physically right next to the sub, I did not hear this noise on the previous day. This hum gets louder when you turn the volume control up. So I started the process of elimination.

1st - Disconnected all AVR components to attempt to isolate - no luck hum is still there.
2nd - Removed power cord from surge suppressor and plugged directly into wall - no luck hum is still there.
3rd - Move power plug to another outlet and hum did not go away.
4th - By accident unplugged LFE cable and hum got even worse.

Is this normal? Do I have a bad subwoofer or amp? The sub has only been in service now for two days - 12/14 and 12/15.