My test bench has for many years had a couple of ground isolated Neve 1:1 transformers between XLR input test sockets and stereo monitors.
Which has never been a problem, but has ALWAYS been a problem connecting any CryBaby Wah Wah pedal.
If you do, the CryBaby resonates at full volume, behaving much like turning a VCF resonance control to full, so it self oscillates. Why is that?
I guess that means you could never directly connect a CryBaby to any transformer balanced mixer input.
Circuit here:
Gareth.