The Suhr looks good, bloody expensive, I bet there's a cheaper option, I remember seeing a Nobels box on eBay that does the same thing (and had level controls as well). I think to avoid the phase cancellation you'd have to run the TF 100% wet  (can that be done, I have a MF?). Back to your original simple split idea: that impedance thing is like when kids plug two guitars into one amp with a simple splitter thing, turn one guitar up, the other loses vol. Anyway, I might even try it to test my inkling.

Cheers.