There seem to be two modes of thought on this question.

Probably the "best" option is to convert unbalanced signals into balanced, by means of a balancing transformer or D.I. There are a bunch of products on the market that will do this kind of thing, or you can roll your own... just buy a bunch of Jensen instrument xfrmr's, wire 'em into a rack panel or two, and voila, you've got yourself a nice balancing network on the cheap.

The quick n' dirty option is to tie the "cold" leg to ground on the output side. I've done this with different unbalanced pieces in my setup and it seems to work OK most of the time... altho every once in awhile you get the odd level drop or impedance mismatch kinda thing.

I'm sure people with greater technical expertise will chime in as well... but those are your options as far as my drug-addled memory can recall. Good luck!

Thanks. Do you know a good source for the Jensens, local or otherwise? And which part number?

Call Jensen, they're remarkably helpful with this sort of thing. They even have a "kit" so you can add "features" to your DI box.

Jensen parts should be fairly easy to find locally. I'll have to ask my tech guru where he gets his stuff. Meanwhile you can hit http://www.jensen-transformers.com for more info.