Small thumping noise.

[Sleestack]

My setup is a B&K 507 S2 w/ Def. Tech. BP 7001SCs. Whenever the receiver switches sources or a function is activated on a device (e.g. play on a DVD player), I hear a very slight thump coming form the subwoofers. I have no crossing lines, no other noise, etc. The thump isn't heard during playback but, I'm wondering if I should be concerned.

[sjdgpt]

My setup is a B&K 507 S2 w/ Def. Tech. BP 7001SCs. Whenever the receiver switches sources or a function is activated on a device (e.g. play on a DVD player), I hear a very slight thump coming form the subwoofers. I have no crossing lines, no other noise, etc. The thump isn't heard during playback but, I'm wondering if I should be concerned.

Assuming absolutely no problems with the RCA cable going to the subwoofer,
I would assume the noise to be a spurious signal of the switch. One source of noise can be a dirty or older switch that gets noisey.

By the way, check the RCA connection on the sub. Sub's then to get moved around a bit, and the RCA connections wear fairly poorly.