Some thoughts:
1. Remember that transformer is, at most, 96% efficient at maximum current (less efficient at lower current draw) and therefore converts at least 4% of watts into heat. Further, a large majority of transformers hum. Its a good idea to have the transformer outside the listening room.
2. If you are going to run a dedicated line(s) some find that there is an advantage (higher current capacity for a given cable size)to wire the transformer primaries at 240v and the secondaries to 120v. 12ga. Romex (a lot easier to work with than 10Ga)at 240V will be plenty for the main service panel line to the lockout switch. Running a single 240V line will minimize gound loop hum rather than using multiple dedicated circuits. (No flames please)
3. For safety reasons (and because of the heat/energy issue in 1., above) the transformer should be switched, not hardwired into the powercircuit. Use a 30 amp (or more)heavy duty lockout switch box (Hubbell, Square D, Siemens, etc) as switch before transformer. These are available at giveaway prices on Ebay.
4. Connect transformer to switched line through twist-lock outlet/plug NEMA L5-20 or L5-30 (Hubbell, Pass-Seymore, etc.)
5. I really (as in really really) like to use NEMA L5-15 (or L5-20 for huge amps) twist-lock outlet/plug as my line component connectors. These are industrial/hospital grade hookups and are lightyears ahead of normal 15a outlet/plugs (5-15R/P) as they have massive contact surfaces and are twist-lock positive connections. Hubbell makes a L5-15 duplex outlet that is a wirein replacement for a normal 5-15R duplex outlet. The NEMA connectors are available through Ebay or any electrical contracting (lighting)store. Also available (though very limited selection) at Home Depot or Lowes.
REMEMBER, SAFETY FIRST. 120V may kill you, 240V probably WILL kill you.
