I've given up on getting my Teac UD503 repaired and while I'm happy with my SMSL SU8 / Mac Mini / Roon / Tidal source into JBL LSR 708P's, my search for a good DAC / Preamp goes on.
I've just come across this box - Project RS2 Digital - while it checks many of my boxes - Roon ready, USB, HDMI...