In reply to:

I have always wondered why speaker cables are strands, not solid, aside for flexibility reasons.



That's exactly why they're stranded... and it's a good reason... unless you want to create a bonzai sculpture out of your speaker wire with solid 12ga.

In-wall installations ending in binding posts at each end: solid is a good choice, though... just remember... keep it away from AC mains, signal cables (telephone/CATV), and fluorescent ballasts. If you have to cross AC or signal runs, try to do it at 90 degree angles. And never run high voltage and low voltage into the same box (illegal under the NEC).

Bren R.