Dedicated line, how many outlets two or four?

I’d absolutely do two as it won’t cost all that much more to run another line.  Also, you can plug noisy digital components, power supplies, etc. into one outlet and other analog components in the other so they’re completely separated.  FWIW.

I ran one 12 awg wire to one Cardas 4181 wall plug. plugged the Saturn 103C conditioner into the wall, then all of my components into the conditioner. 

I did two circuits because it was as much work to do two as it would for one, I did 20 amp circuits with 10/2 Romex, audio grade receptacles and power conditioners plugged into each circuit. My amp is plugged into one circuit and everything else into the other circuit. It made a significant difference.

Three circuits for my main system. All 3 are 20 amp, 10-2 romex, using high quality medical outlets. Two outlets per circuit although only one gets used.

One circuit is for the sources all plugged into s PS audio P12.

Each power amp with sub have their own circuit and each are plugged into PS audio P20's. It is primary overkill but WTH.

We were redoing a basement and we added a sub panel. Because the cost difference was minimal, I added 5 dedicated lines. 1 for the monoblock amps, 1 for preamp, 1 for digital, 1 for subs, 1 extra, along a side wall, in case I am able to get my gear out from between my speakers and along the side wall.