Dedicated 20 Amp Line for Audio

Both of those on the opposite rails to that of "noisier" items on the panel.

that's fine, but make sure your 20A audio lines are ON THE SAME 110V RAIL/LEG.

Also, I would not use 14/2 Romex or stranded wire.  You really need 10/2 Romex (Romex is always solid-core which is better than any armored stranded wire).  If you can't do 10/2, then 12/2 is acceptable. 

I don't know that you need a separate 20A line for each device like hilde45 recommends.  It's all about current draw.  You could probably run all source/digital components on one 20A circuit just fine.  The other 20A would go to amplifier only. 

That being said, I have six 20A circuits run to my room.  Each amp circuit only has one or two amps, but I'm totally overkill on my setup.  You can probably run two small/medium sized amps on one 20A circuit just fine.

Another option:

https://www.vhaudio.com/wire.html#bulkacwire

VH Audio sells cryogenic treated 10 awg romex wire.  It's a lot more expensive, but if you want the best that's the way to go. 

I am not currently running cryo-romex in my setup at this time (maybe in the future).

14awg is the MINIMUM you can do for a 15A circuit.  If it's a long run, then 12awg is recommended.  That is based on electrical code requirements. 

However, there is a definite difference in current capability between 14awg and 12awg romex, even on low current source components.  I've tested this in my room when I tried 14awg romex to my preamp/processor.  It just did not sound as open and the sound did not hit with as much authority as when I did a 10awg romex. 

You can use 8awg, but you are only going to get stranded wire and you will need to run this in conduit (per electrical codes).  Only romex can be run bare through walls and in ceiling/attic.  I would rather have solid-core 10awg or 12awg romex than stranded 8awg (but there are others with different opinions).

A note on 10awg romex.  Yes, the wire is extremely stiff and you may not be able to install it.  You CANNOT fold this wire when pushing the outlet back into the box.  It is just too stiff.  When I did mine, I had to run the Romex straight through the wall from behind into the junction box and then "square bend" one wire at right angles so that there's enough space.  A 12awg romex would definitely be much easier to handle.

Audio Sensibility in Canada does sell cryo-treated 12awg romex:

https://audiosensibility.com/blog/accessories/parts/wire-and-cable/#!/Cryo-Treated-Electrical-Cable/c/5828813

It's in CAD currency, so 1.90 CAD is $1.50 USD (per foot for the 12awg romex).