I have a full set of Nanosat speakers and recently discovered a hum coming from the Nano-sub.  I can hear a faint hum if I plug in the sub to a wall outlet but keep the sub power switch turned off.  The hum gets a good bit louder once I flip the sub power switch to the "auto" or "on" positions.  This happens regardless of whether the speaker cable is connected to the Nano-sub.  The hum is also present regardless of which power outlet I plug it into in my house.

Is my sub starting to die a slow death, or is there some way of fixing this issue?

 Thanks for your help!

Mirage tech support responded back to me and said that there must be an issue with the internal sub amplifier.  If it's out of warranty, you'll need to take it to a service center for repair.  I'm considering purchasing a replacement sub vice repairing the one I currently have.

I think we need to push back on Mirage a little... my sub is only 13 months old and I am seeing this problem all over the place.  I think its simply a poorly made product.  Love the Nano Sat's though.  The speakers are great... it's the amp I have a problem with.

 I bought Mirage S10 in 2005, but actually used it for about 1 year.  My amp is out according to MIRAGE.  Depending on the cost, I am going with HSU or SVS Subwoofer!  No more MIRAGE for me.