Mattcone
Definitely, go with 20A.
While that's going on add in a good outlet... or two, making for a four gang power portal. Hospital grade or up.... Porter, Oeida, etc.
One never knows.
Wires do make a diff. How much depends on you, your gear, and how much you wish to invest there.
Get a good to as good as you can justify, speaker cable. Then address the power cables... lastly, do the interconnects.
Lots of info here on isolation and it's various applications & philosophys. Resonance, physical, and electrical.
I've determined no actual ratio for cable costs vs. component costs. More importantly I address each component individually in that regard.
There's about 81.705 gigazillion cables available. ya can't try em all so get in where ya fit in there as well as you can justify it.
Such a tidy system as yours shouldn't pose too many problems with wires.
Good luck.