What should I upgrade?

You don't mention cables....My Ayre greatly benefited from good power cords.

I am currently using Cullen Power cables. . I have tried Acoustic Zen Tsunami, PS Audio AC12, Zu Audio Bok and Cullen Power cables. I was not able to hear much difference. The Cullen and PS Audio seemed to make my system fuller with tighter deeper bass. They both sounded the same to my ears. The ZU and AZ were a bit leaner with a more focused high end. All of these differences were quite minute though. I think the fact that I have dedicated circuits running to my system might make power cable difference less discernible?

I think you should wait and upgrade your Calypso or Atlas to Eclipse version, which will be a bit more expensive than the Signature upgrade.

Wow I did not realize a new upgrade was in the works. Sounds like I should wait for sure.

The upgrade is available. Take a look at the Aesthetix website. aesthetix.net

I called Aesthetix regarding the Eclipse upgrade for my Calypso. It is out of my budget ($5000) I think I will stick with the Signature upgrade ($2500)  for now.