Stranded vs Solid Copper

I did the same thing a few years ago. Use 12awg solid copper Romex and connect to an unused circuit with 20 amp breaker. By the best breaker you can. Try to use the leg with the fewest appliances and large power draws.

Thanks for your response.
Luckily the circuit is 5 outlets with one overhead light. I never turn on the overhead light and typically use one lamp. It would be nice to have a dedicated circuit, but I didn’t build the house.
What I’m asking if 12 gauge stranded wire has inferior sonic characteristics? It would make a more flexible cord. I’ll look into a better breaker.

 IMO it depends on your system..The more resolving the system the more likely to hear a sonic difference IMO favoring 9nines solid or better...