Dedicated 20 amp circuit. 10/2 or 10/3?

Oh...and if you move/sell and/or bust the lease with your 'loud *ss music'....restore it to a 'normal' 220....With the correct f/m plug....

For most folks, a 12/2+G or 10/2+G run from the 'quiet' side of the panel is perfectly adequate. If you have big power hungry monoblocks, then a 10/3+G providing 2 circuits is still more than adequate. 

In an existing house you may not have panel space or the luxury of picking a 'quiet' side of the panel and electricians rarely leave service loops adequate to rework loads by re-homing breakers. In that case an solation transformer although hugely expensive may be worth it to you. For most, good power conditioner will have to do. 

In any event, a digital oscilloscope, preferably with spectrum analyzer capabilities is really the only way to see how clean or dirty your power actually is. 

10/2 and run more than one dedicated line while you are at it.

I have a pair of class A mono blocks, I ran one 12/2 conductor twenty amp circuit to a Cardas 4181 receptacle. From the wall the power cord goes to the power conditioner, then all my gear plugs into the PC. Running full load with some volume, I am pulling 9 amps of current . Not sure what your gear is? #12  is adequate for most systems. But run cable for where you will end up.

Keeping all the audio on one leg helps reduce ground loops. Your system is probably not going to draw enough current to need both legs.