DAC/Preamp Question

I love my system most of the times, but like most of you, I’m always thinking of improvements.

I’m currently using the Cambridge audio 851N as both the DAC & preamp and will need to get a new preamp if I want a better DAC. I’m wanting to keep the 851N and use it as a dedicated streamer for Tidal, which means connecting a new DAC to it via the AES/EBU port. Has anyone done this, and if so, how was the SQ? What DAC did you use?

For a new preamp, I’m thinking going hybrid and keeping my Parasound A21+ power amp and adding a tube preamp with it. Anyone else use a tube preamp with the A21+? If so, what tube preamp? Any experience with the Primaluna line with the A21+?

One of the reasons I started with the 851N as the preamp was to make the system as simple as possible. My reasoning was that fewer parts = less chance for noise = better SQ. What do others think about this? Is introducing a good tube preamp helping or potentially hurting SQ (Ignoring any differences in DACs)? Would I be better off buying a better DAC/Preamp combo? If so, which one?

FYI - Speakers = ML Classic ESL 9; Power Conditioner = Furmen Elite 15 PFI; Cables = various, but mostly Pangea. All digital music via Tidal or ripped CDs from NAS. I listen to whatever sounds the best – today that’s Boyz to Men and the like, but tomorrow it might be Led Zepplin or Alan Jackson. Room = 15 X 25 X 15 (No treatments, but boatload of furniture, flowers & other sound absorbing stuff). Speakers face perpendicular to the long walls.