RichK wrote:
Well, the line input is in the subW, from which it normally goes to the L&R
speakers.

Hmm.. you probably mean that signal is normally fed there from L&R
spkrs?

The amp is really in the subW, only the controls are normally in
the L&R speakers (well one of them).

Then, I think that u just need to feed line signal to the input :-) I
don't think that you really need any other controls than volume in the
subw, since it plays only sub-low-range.