@gelle with that type of budget my personal first choice would be the combination of the Chord Qutest and the Curious USB Cable for use with the Roon Nucleus. That is what I am using in my main rig. Having said that, your budget gives you plenty of other good options .... and a lot depends upon what you are looking for in terms of features from a DAC.
Other choices that I have considered (both new or used) include the very fine Ayre Codex and products offered by Schitt and Mytek among others. But as I said above a lot depends upon what features you value as well as the type of sound that you prefer. Also very much like the Bryston products. I have a BDA-1 (used to be in my main rig, now in a second system), but in your case you would require a BDA-2 or above to mate via USB with your Nucleus.
Other choices that I have considered (both new or used) include the very fine Ayre Codex and products offered by Schitt and Mytek among others. But as I said above a lot depends upon what features you value as well as the type of sound that you prefer. Also very much like the Bryston products. I have a BDA-1 (used to be in my main rig, now in a second system), but in your case you would require a BDA-2 or above to mate via USB with your Nucleus.