If you have two pieces of earth-connected audio equipment, you can get ground-loop hum. It's not a good idea to break safety grounds at the plug, and instead, best practice is to use an audio isolation transformer.

Audio isolation transformers are pretty expensive, which leads to two questions: one is "can I build my own?", and the other is "should I really expect this piece of kit to do what I want". One way to handle this is to make a quick model, which you can do in Simscape.

Audio isolation transformer data sheets are generally not particularly rich, often just giving you an impedance rating and a frequency range, but not a lot else - you won't often get a nice equivalent circuit network model. With a bit of first-year EE maths, you can calculate something that gives you an idea of the ideal behaviours, though it comes with the caveat that it's just the electronic version of a "back of the envelope" calculation. However, this might be all you need - if you're trying to solve a similar problem, why not give it a try?