My supernova 12" earthquake subs are suppose to shut off when no-signalis detected after 30 minutes or so, when the receiver (Yamaha RXV-1400) is on, but no source output, the subs go into stand-by, like they should, but if I shut the whole system down, the subs "greenlight" the entire time and have a hum, I am using a shielded sub-cable of decent quality, any suggestions??

Have you tried a "cheater" plug on your power cable? I needed to use on with my Hsu.

I don't know what you mean by a "cheater plug" I have a single (mono) sub out on the receiver cable, to the LFE connection on sub-1 with a y-connecter to sub-2 connected in the same configeration as sub-1.

This is what Spiff is talking about.Also try disconnecting the cable or satilite reciever from the chain of equipment and see if the hum goes away.

The plug on the amp is already a 3 prong grouned, looks to be #10 wire (pretty heavy duty) 110/220 swichable, and the outlet is gronded, rewired averything a few years back.

I know...the cable on my Hsu is a 3 prong grounded plug as well. I need to use the "cheater plug" to convert it to a two prong plug. Don't know why...but it works.

What the cheater plug does is float the ground.When using it don't ground the tab to the outlet.If you do you will still have a ground loop.Try disconnecting the cable or satilite reciever first and see if the hum goes away.