Speaker Cable Recommendation to upgrade Tribuataries in Wall UL rated cable

To be honest and given your equipment I’m surprised you think it sounds a little thin, but I’m not familiar with your interconnects or speaker cable. Given what you’re looking for I’d highly recommend these Acoustic Zen Absolute cables (I’m assuming you’re looking for 8’ per cable), and if they don’t work out you can sell them for little/no loss. I think they’re like $3900 new.
https://www.audiogon.com/listings/lisb67d0-acoustic-zen-absolute-speaker-cables-8-feet-demo-with-warranty-ac-cables

Kubala-Sosna is another one worth looking at and here’s a pair of their Emotion cables in your price range…

https://www.audiogon.com/listings/lisb7055-kubala-sosna-research-emotion-speaker

Cardas cables would be another brand I’d explore, and I’d defer to @ghdprentice as he knows a ton more than I do about their cables and specific sonic flavors.  Any of these would likely be a nice improvement over your Tributaries in-walls I’d think.  Hope this helps, and best of luck

Take a look at this neaotech cable...

• Neotech bulk OCC cables

The OCC copper should imrpove dynamics and the geometry should improve clarity and imaging

Regards - Steve

I have heard Tributaries cables and never found them lean sounding.  They make the McIntosh branded cables which can go for thousands of dollars.  My personal choice is Canare 4S11 cable.  The break in time is around 500 hours but they sound great right out of the package.  I bought an 18 foot pair of them terminated with banana plugs for $120.00.  They have been in my system since January 2021 and they are the “keepers” I had been looking for.