220/240 sub panel, and # 12 copper romex for the 120vac receptacles. I use 125vac copper hubbarts.
The thing I don't like about # 12 is roughing in all the pigtails. The best of days twisting wire nuts leave me crippled for a week. Not the good old days after 49 years of pulling wrenches. 15 minutes 3 sometimes 4 times a day, from 10-16 hour days for 49 years.
I don't use the basement or attic for sound but both have subs/220/240 and # 12/3/g copper romex. There are 125/25 amp outlets every 4 feet. I can add 220/240 to any outlet the wire is in there or split the two each having both L1 and L2 from the main in the box. L1 is always the left side of the room L2 is the right side. I don't mix the two. It can cause noise.
Regards