It is pure BS that a $5,000 cable sounds better than a $500 cable. Pure BS. I expect this post will be likely pulled because I have stated a plain fact bluntly that some advertisers take offense to-- especially those that make wild, impossible to substantiate claims for products that they sell for obscene profit margins. Yes, I do feel it is a little obscene to create a product that, lets say costs a few hundred dollars in materials and labor only to be sold for 10x-50x that at the retail level based upon fantasy claims that have nada to back them up.
The OP has a very nice system and no doubt small changes in the sound will come from trying different cables-- but when you receive advice like- spend more than $2k per cable to get better sound-- that is, again, pure BS.
So spend whatever you want, but do not for a second believe anyone that makes the claim that by spending more on cables that it will guarantee you a better sounding system. It will if you are using really cheap cables, but since you are already using very good cables, what you should expect are differences-- and they may be real or just psychoacoustic-- so I recommend "living" with the changes for a while to get a more complete sense of whether you prefer the sound as it is or as it was.
In the end, sometimes all someone wants is change for change 's sake, and there's nothing wrong with that either.