Dedicated line, how many outlets two or four?

Doesn't matter as much as conduit.

Jumia,

Go by wattage.  A 20 Amp line should be around 2,400 Watts.  In a typical home a 20 Amp line may be wired to four or more duplex outlets for convenience.

If you are running from 1 breaker, you would use 10/2.  If you were going to run 2 different circuits (on 2 phases) then 10/3 is convenient.

I put in 2 circuits so that I can put junk like switching power supplies for TV streamers on the other circuit.  I put six outlets on each circuit.  However, once you have a good poer regenerator, you'll find it is plugged in and most audio components are plugged into it.  Mine has 10 outlets on it and all but 1 is full.  Once you go down the high end power supply rabbit hole you'll need a lot of outlets.

I used 10/3 just as Erik describes above.   This has the added advantage of giving you access to 240V if you have a piece of european gear.

Just one item should be plugged in .. a very large power conditioner/generator. 

I did 5. 

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. 

Sub panels, especially with long runs, are the way to go.

Anyone use Pangea outlets? Trying to decide about audio premiere - $25 or the audio Premier xl Version which is $100. The hundred dollar version is gold plated beryllium copper which sounds really really fancy.

Three 20amp circuits 10/2 Romex, Oyaide R1 outlets, one circuit for power conditioner, all equipment except amps, one for monoblock or stereo amps, one for streamer lps with 30amp capability. Amps and high current power supplies not good on power conditioners.

Two good quality hospital grade outlets is a good choice!