Separate Dac, and what kind?

I believe a separate dac would improve the sound quality of my system, but I simply don't understand much on the digital side of equipment.  I have a sonos connect (for wifi streaming from router in other room), and a 15 yr old Sony scd ce595 connected to relatively new bryston bp6 preamp and bryston 3b cube amp.  Speakers are aerial acoustics model 6.  Blue jean cables, interconnects.

There is no digital input for a direct connection on back of sonos for an Ethernet from router in bedroom to the sonos in the living room (its a 45 ft run, and I don't want to bother with wiring anyway).  I mention this because a hard connection might sound better.  I have to use the sonos wirelessly for a streaming connection.  It only has digital and analog out.  Of course I use the analog out since I am using the dac in it.  The cd is connected directly to the preamp (again using dac in cd).

I don't mind spending $1500 on a new piece of equipment.  I am considering shitt.  I listen to jazz mostly since the recording are always better than rock, pop, blues etc. (no symphonic music), whatever the source.  And I used to play jazz, big band.  This equipment is very transparent, I sent back a new bp17 because it had a somewhat synthetic quality to it (thought I would mention this, Im striving for an organic natural sound).  Any suggestions?  I would appreciate any ideas.