I ran 30 amp sub box from my main panel using six gauge wire.
10 gauge wire for all of my dedicated lines and used 20 amp circuit breakers.
Digital should be on a dedicated line all by itself.
Just a suggestion but amp by itself, preamp and TT could be on the same line.
One line for the self powered sub.
Would not hurt to throw in one extra dedicated line while you are doing all that work to have just incase you want it, or to experiment with.
10 gauge wire for all of my dedicated lines and used 20 amp circuit breakers.
Digital should be on a dedicated line all by itself.
Just a suggestion but amp by itself, preamp and TT could be on the same line.
One line for the self powered sub.
Would not hurt to throw in one extra dedicated line while you are doing all that work to have just incase you want it, or to experiment with.