Thanks again for all the suggestions. I figured the best approach was to just start trying different cables. To that end I started with stuff I could get my hands on locally: a roughly $50 Pangea model, then a $350 Cardas Clear, then a $650 Audioquest Vodka, and finally an Audioquest Diamond (dealer demo for $1200, normally $1999).
Before this I had been using a Wireworld Starlight 8 which I think was around $320. It seems that in my system, each one of these cables makes a fairly obvious contribution to the overall sound. Roughly on the same level as changing analog interconnects or AC cables. I can’t say that will always apply to every setup but for me the impact is clear enough.
It doesn’t end up correlating to cost either. I think the Vodka works best, then the Cardas, then maybe the expensive Diamond. Despite being outclassed, the Pangea is an enjoyable cable that I might choose over the Wireworld depending on my mood.
My journey is not finished, I plan to order some other options that I can’t find locally. So far I’m interested in models from Fidata, Curious Cables, Pink Faun, and maybe a JCAT. Will come back and update my thoughts when I can.