Quote Originally Posted by grumpy View Post
More fun:
Also possible to use both BX63A sub outputs (to get the Y out of the variables). just swap the sub's speaker lead (plus to minus or red to black) on amp channel connected to the BX63's "-" output channel.

Faulty speaker (e.g., voice coil), or loose-ish connection in it's cabinet (terminal panel to driver)?

Certainly tough diagnosing via email.

LOL yes it is!!

Rob