speaker cable that would work under a rug

Goertz MI 3 Flat Ribbon

@tksteingraber +1 if you want to go premium. Check the Cable Company.

I have runs of about 14 feet of Goertz MI 1 flat copper under family room large area rug. Works great.

Happy Listening!

Any good heavy quality cable. I bought a roll of it 5 years ago for an under the rug run in my living room for my rear surround speakers mounted on the wall ing a large area throw rug over tile and it's worked great.

Can you get in the attic to run them?

That's what I did, through the attic and down inside the walls. Very Clean!

There is a company called "the cable Company. https://www.thecableco.com/

They have an excellent selection of all sorts of cables. I have had good luck with the Goertz cables. They are specifically designed as being flat, as in wafer thin flat. I believe if I remember correctly you buy by the foot. Good luck.