Alex may have a more detailed answer, but IIRC balancing can involve having balanced cabling throughout the headphone, and is not just a matter of the termination (please correct me if I am wrong). An option you may want to pursue instead is having the cans recabled as balanced and have Alex whip up an
XLR--->1/4" adaptor cable for use with SE amps.
I recently used this when testing a set of L3000's which Alex recabled and it performed admirably. The build and sound quality were, of course, impecable
. It's also more flexible as you have the option of using it with both types of amps at will, and only need to add or remove the adaptor cable from the chain.