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

One can run 10/3 romex for 220 single phase to a location, and run with it a 12g. green ground with it.  Perhaps not 'according to Hoyle' but at the business end one can 'split' into 2 - 110 circuits and still have the 'safety' mechanical ground....

Label what you've did/done....at each end.....

It's not nice to 'leave mousetraps' like that, and keep your amp loads balanced.

Cooking one side generally takes the other with it...just to make the point....;)

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.