MOTM

>So, I think Paul's concept of a switching jack is still best...

Absolutely, no need for the switch.

>... but I think the "switch jack" should be the second output not the
first.

But I don't get this. Surely the top output should be the sum of the top
row of inputs. Inserting a jack in these automatically disconnects this
from the next three. Its also easier to do, since you can do this with
the NC contacts in the 112A.

Its what I would do :-)

Regards,

Tony Allgood  Penrith, Cumbria, England

Oakley Modular Synth and TB3030:
www.techrepairs.freeserve.co.uk/projects.htm
My music: www.mp3.com/taklamakan