Subwoofer hum
 

I'm planning to add just a basic subwoofer and amp to beef up the low end. Manager at the local audio shop warned me that by adding a subwoofer to a factory Bose head unit like in the 8 will generally lead to introducing a barely audible low pitched humm in between songs or when the radio is turned down. Shouldn't be noticeable while listening to music in general but he still wanted to warn me about this. Has anyone else noticed this? Is there no way to avoid it? Does he really know what he's talking about?

I used a Peripheral Line Output converter (LOC2)... no hums.. just nice.. clean.. pounding.. BASS ;)

I just installed a sub last weekend. No hum in between songs...sounds GREAT, actually. I didn't use a LOC. I just wire tapped into the preamp inputs that go into the existing amp between the rear speakers, using an RCA cable that I cut one end off of.