The sub Im after although very clean has been storage for two years and the seller no longer has an AVR or Bluray player to test it. I just came up with a test method and I tried it on my sub and it works. I'm using a portable bluetooth receiver module that has stereo output. I use this module to give me Bluetooth capability on my older AVR which lacks the capability. I know I need only to connect left or right stereo output from the bluetooth receiver to the LFE left and right input but in my test I connected both. I then streamed a blues song with lots of bass from my tablet through the bluetooth receiver into the sub. The music was very muted and very narrow banded in sound as I expected it would be but when the bass kicked in on the song, I got lots of bass on the output. Its a hack I realize but it will tell me if the sub is working and if crank the volume loud enough, it will also show if the driver is damaged. Just thought I would share this hack.
