The wire was 14guage and I still have a lot of it left. If I were to strip the ends and twist about 2 ft extra to each and cover with shrink tube or electrical tape, would that work fine?
These will be my 7.1 rears.
It will work.
There is one concern. If you just twist two copper wires together, they may (will?) eventually develop oxidation at their surfaces; this will impede current flow through the mechanical connection and lead to distortion. Soldering the connection prevents this.
I didn't hear any negative effects of using hand-attached copper wires after eight years on the coast(s). Oxidation is definitely more than a theoretical concern but that doesn't mean it's always a practical concern.
I think if a connector is designed to be soldered, it should be. I didn't even consider connectors with set screws.
Thanks for the clarification.