I understand from Pierre Gabriel that the DA 88 Signature has "a new design" with updated circuits and topolgy and is specifically designed for KT 88s. However, he makes it clear than it can play other tubes, including my favorite EL 34s. The DA 60 is designed for all and any of the output tubes. I have the DA 88, and it is still brand new, with about 100 hours on it. Nevertheless, it is dynamic, punchy, has brilliant soundstaging and is seemingly powerful way beyond its stated nominal 60 WPC.I have only used the stock KT 88s. (? origin of tubes - not disclosed by Jadis) So far, an incredibly impressive perfomer than makes my hair stand on end....
On the other hand, my friend Trelja thinks the same of his DA 60 with JJ EL34Ls......
The Jadis magic (I had the JOR and only sold it beacuse it isn't auto-biasing)is certainly there in spades. Only time will tell me - and maybe replacing the KT 88s with JJ E34Ls - whether it has the JOR's liquid midrange magic - but in all other respects, it reigns - dynamics, bass, musicality, PRAT, harmonious coherence - but I have not heard the DA 60.
My feeling is you cant err with either, and it certainly wont be put to shame by any separates I have ever heard.
For pricing, talk to Pierre.