Speaker Cable Recommendation

Consider vintage Western Electric cables.

There’s a seller here.

Have you rolled those 12AU7 s?

"Not a great room". It seems counter intuitive to me that you would want to spend up to $1000 to counterbalance the room problems, especially when expensive cables tend to be neutral and likely to expose problems in you room/system. In your place, personally speaking, I’d cheap out and get some Belden 10 ga cables sold by Blue Jeans. They might just do what you want, and if not you won’t have spent much money. The Mogami (12ga) is a good option too, but it's different from the Belden in that it is more info rich in the mid-range, but not high on warmth.

Very pleased with my new Anti-cable 3.1 reference.. a bitch t install on my Thiel CS2s but the sound stage and imaging are worth the effort!

Canare 4S11 cable.  You will thank me later.

Cables can't fix the room. I second the Mogami or Canare recommendations and suggest you consider using the funds saved to add a little acoustic treatment to the room. Carpets, drapes, acoustic panels, bass traps, whatever. GIK or ASC will make plans for you for cheap. You don't need to follow them, but they'll give you ideas. The improvement will far exceed what any cable change can provide.