Stranded vs Solid Copper

Not sure how the sound is affected between solid and stranded but the best thing for HIGH current is stranded because of the skin effect of AC voltage (it actually travels on the outer layer of wire). 

This is I know from being an industrial electrician. 

Myself Use Verastars excellent high purityCopper foil speaker cable,and Silvergold alloy foil interconnects . A flat foil has more surface area then  equal size awg guage wire.and very thin diaelectric. That may why it sounds very balanced . I have had several very good brands for me this is high enough 
in quality without breaking the bank.

Your decision on solid core is good. If you ever wanted to go stranded, Litz 9.5 awg from partsconnexion would also work great. You do need a soldering pot to prep the ends. Each individual wire has a coating. It must be removed.

If your going to build a box, do an internet search; X capacitors and Y capacitors. These little beauties remove hash from the power lines. Unless I'm mistaken, the X caps go from hot to ground, and neutral to ground. The Y caps go from hot to neutral. A world of difference almost forgotten in the diy world.

@coachpoconnor said:

I’ll look into a better breaker 

There is only one correct breaker for each panel. That is the one that is the correct current rating (regular/GFCI/AFCI) specified by the manufacturer of your panel. Any other breaker is the wrong breaker. Period.

sleepwalker65

There is only one correct breaker for each panel. That is the one that is the correct current rating (regular/GFCI/AFCI) specified by the manufacturer of your panel. Any other breaker is the wrong breaker. Period.

This is mistaken. There are instances where there are alternatives to using the OEM's breaker. For example, Siemens makes substitutes for some Square D breakers. UL listed, too. See this.