Edited by grokit - 3/8/11 at 8:12pm
Yes, I think this should be an easy mod to float the output. Which, after talking to Craig, is what Eddie Current does (his 1/4" jack disconnects the common "ground" when nothing's connected). Craig was confident in the safety, and he's got way more experience and knowledge. There's already a 4 gang stepped attenuator. Just connect the wires directly to the XLR. Or you can get a 1/4" jack that disconnects ground when nothing's connected. That way you can play with single ended vs balanced with a dummy plug. I don't have my WA22 anymore, so I can't check out the wiring. I'm sure someone can do it fairly easily.
(WARNING: some regard floating the output as unsafe. Should there be a short from primary to secondary on the transformer, then full high voltage would pass to the headphone. Which in that case, your headphone would stop working. And if you just happen to open your headphone or sticking a screwdriver in there, then you'll get shocked. Or you stick a paper clip into your XLR socket with a nice wet finger. Or your headphone cable isn't able to handle the high voltage)