Using both the Balanced and Unblanced inputs

It works that way on my Mk IV. But don't assume ;--) Try it, with both volumes turned down.

I had both the balanced and unbalanced inputs connected on my Basis phono stage when I was comparing cables with no problems but as Nsgarch says try it carfully.

Call the manufacturer.

I have run parallel SE + BAL systems in the past, coverging at the POWER AMP. (CDP and PHONO AMP each go se to one PREAMP and bal to a 2nd PREAMP, the first PRE goes se to my POWER AMP and the other PRE goes bal to the same POWER AMP.) I always checked in first. Some said "no sweat", others said "no way". IIRC, it's a dicier move on outputs than on inputs, but I'd spend the dime on a call to be safe.

Good Luck

Marty