I recently went through my station fixing all the years old AC hum problems. I used probably fifteen 600 Ohm 1:1 transformers, in addition to some work on a couple of linear amps with AC issues. Now the audio is much better. If you are concerned about audio runs, the first thing you should consider is converting to balanced feeds.
Here are some various balanced and unbalanced grounding configurations, note the labels at the very top of the columns.