Why do you want to go split that perfectly good mic anyway?

[audioboffin]

One of the reasons why trucks run bigger 3 phase power iso transformers is to give the gear some immunity from switching spikes etc from other sources, for example when air conditioners kick in and out. It's for this reason that a lot of mobile recording trucks have air conditioners that don't switch off. A transformer can act as a choke, suppressing certain power disturbances that might otherwise be imposed on the line, and as a very rough rule of thumb, the bigger the transformer the greater the smoothing effect.

Back to the split question, and for somewhat similar reasons, many engineers will favour isolation transformers in the audio path over other options.