Hi Charles:
Excellent suggestion. I am a bit late to the party but have been thinking about the head output mod for all Studers. It would have been great to discuss the experiments Doc B had been conducting when I saw him at the CES but as it normally goes at these shows, it didn't happen. However, Doc did pointed out this thread for me to see what he has done so far.
One of my key concerns is, as with other tape decks, when one switches the head wiring on A810 (accidently...) with the deck's main power and the outboard tape preamps power on, will there be a surge or any current going through the repro head that will magnitize it? The 4PDT toggle switch I had used would short before switching and didn't cause the problem but with your idea of using two 1/4" phono jacks, I am not so sure.
In an A820, there's enough room to mount a toggle switch near the pre-preamp input terminals but phono jacks would have to be mounted in the rear of the machine with factory I/O terminals.
