Dedicated power

Stay with one line, a 20A. This will avoid ground loops. Just buy a Niagara 1200 and that will give you many receptacles to plug gear into. Also, I’d recommend the AQ Edison receptacle for the one line. So right there you will still have the extra receptacle above or below the Niagara upon plugging it in. Lastly use at least 12/2 (20A/usually yellow) Romex, not 14/2. Do it yourself, it is easy/saves lots of money.

Do you have an audio system or a welding machine ?

If you really need 30 amps, you may consider changing your system.  It is more like a PA system than an audio system :-)

Besides, sockets used for 30 amp connections will not accept normal amplifier plugs.

Wow. 30A line will only allow you to draw current past the 20A without damaging wires or blowing fuses or circuit breakers. If you are drawing less than 20A you won't hear the difference with all else being equal.so for Motorola your amp won't "strain" because of lack of power if your amp draws that much power it would blow the fuse or circuit breaker.

Spellchecker. Lol that was mofojo not motorola..

cakyol
  "Do you have an audio system or a welding machine "?

Well said, and an excellent point.