Consider this dual use concept for potential resale in future: one large space for rehearsal which doubles as a home theater, with smaller control room for recording and home theater electronic gear. Glass window in wall between the rehearsal room and control room. I have a similar set-up at home. For the investment you are gonna make, you want to make it as appealing as possible to a wide variety of people. At least get the wiring in the walls and you could do the theater later. You might also get it plumbed for bar and bathroom and get the whole man-cave vibe happening...