My electrical engineer husband was a professional theater techie in NYC specializing in lights and sound. He didn’t need a degree to do that (when he did it), but he had a ton of experience. His major in college started as chemistry, then physics, then EE. But his main fun thing to do was lights and sound.
I will say…at his first college, he spent a LOT of time doing theater techie things (as noted…it’s time consuming)…and that was not favorable for his actual classes. He actually left college for about 8 years to do only the theater techie stuff.
What does your son hope to do with a combined degree in these two fields? Does he want to design theaters (DH did that and loved it…once he had his EE). Does he want to work in theater doing lights, lighting design, sound, etc? That doesn’t require a degree AFAIK.