At one time my main system was all battery powered. Computer, Dac and amp. My battery was 40 amhs and if you use a ctek 7002 charger you can leave it charging even when playing music as completely quiet.
My original system had a 200 amh battery bank that I charger with my solar system, but I found it to be way over kill.
In theory any audio gear can be modified to run on batteries because the a/c is converted to d/c in the gear.