This is intriguing. I have an Excel that came with the Bass/Treble circuit and which I swapped in the Filter w/Q circuit. In studying Flip's pictures, I?d need to (gulp) drill couple of holes and I would need (what?) to marry the two circuits into one?
 
Heck of a job, Flip!
 
Reid

Ah! Post posting the above message, I did a search and was reminded of the Y-conversion cable which I later saw the Flip referred to in his posts. Running a step behind today! LOL