I'm new here. I've bought SB16 Ultra few week ago and pretty happy with it. However, I just realized it has humming noise, it sounds like the white noise from TV or radio. It makes me feel like there's a fan running inside the sub constantly. I've contacted SVS customer service and they were very helpful, after few emails, they decided to send me a new amp to try out. However the new amp does the same thing. I've tested the sub when it only plugged into outlet.
My question is: is there any level of humming sound acceptable for sub? or it's by design?