Are you looking for new features like Roon or just interested in getting better sound quality?
How are you driving your DAC from the Bluesound?
To get significantly better sound, you don’t need to replace the Bluesound if you like it. It is not optimum to use the server as a DAC as well IME. Just get a good DAC and connect to the Bluesound with a good S/PDIF coax cable like this one:
If that does not deliver what you are looking for, then add a Synchro-Mesh reclocker for $599 to reduce jitter from the Bluesound to 20psec:
As for DAC’s, I don’t know what your budget is, but the Border Patrol is very popular, particularly if you don’t care about DSD or 192 PCM.
Other options from Ressonessence and Chord are good choices that support higher sample-rates.
I would be more inclined to do as you suggest and just get a better DAC for the Bluesound. However, I am removing it altogether. I guess I could just get another one but since I will be having to replace the Bluesound anyway I just thought I would consider something different. Thank you for your recommendations.