Does High End In Wall Speaker Wire Exist?

Transparent sells lengths of in-wall cable.

Analsys Plus and JPS Labs makes speaker wires for just that application.

I vote Transparent Cable, great match for Wilson speakers. You run lengths of their in wall cable and then it terminates at a wall plate. From there you connect short lengths of speaker cables with the network boxes on that cable to the wall plate and hook it up to your speakers. It's a great upgrade path too. Buy the best cable you can afford for the in wall portion and then upgrade the network boxed portion as funds allow. They have different levels of "tails" just like their normal cable line. Start with Super now and upgrade to Reference later.

Thanks guys - those are the three I started with and checking with the A'gon body of knowldege for additional options. I just took a look at the space in the basement and it is 1/2 exposed floor joist and 1/2 finished with a 1 foot air gap. Wonder if I really need in wall rated speaker wires?

I agree with Tubeking that conduit is the way to go.

It allows you an opportunity to change wires should you ever decide to change speakers, and the wires that work well now, don't with your future speakers.

My two cents worth.

PS I'd go with 2 inch conduit if you can. That allows you to use most cables, no matter what the thickness or stiffness.
í-AAGood Luck!