Recently did a garage to listening room conversion installed 2 ea 220V dedicated lines, one on the amp wall and one on the front end wall. 6 each dedicated 117V lines (20A) 2 on the amp wall and 4 on the front end wall.
If your building a house consider running a 60 Amp, or larger, sub panel to your Listening room then run as many lines as you see fit from there. ( I did it the other way around - installed a sub panel to feed most of the rest of the house, then ran all the dedicated lines form the main panel). If you go this route you could consider installing a isolation transformer to feed the sub panel.
Csontos - theres no real danger to running 30A line but the connectors/outlets you'd be required to use upholding code would not be practical.
Good listening
Peter