Almost none. I have been working with Tempo Electric, a company I heard about here, perhaps from Pete, in upstate NY on a new set of cables for the system—almost entirely for sentimental reasons, as they were based in the town where my two older daughters grew up, but also because I liked how they articulated their engineering philosophy—but that project is not done yet.
I had them build a new set of ICs in order to complete the integration of the headphone rack into the speaker system, and these sound marvelous, especially on the Susvara, but also discernibly so on the Stax 9000. They also built a set of AES/EBU for the connection of the DAC and Upsampler, but I am uncertain of any sonic difference as compared to my previous DH Labs Silversonics, other than expectation bias; as I said, this was primarily a sentimental project. Right now, they are working on the clock cables, which have proved a bit challenging, but I have no doubt we will get there.
Other than that project which began last December, I have done nothing but enjoy my system. My severe GAS has been directed elsewhere. 