If you have money burning a hole in your pocket, the obvious areas are the power amp or source. If you want a variety of web streaming sources, a new generation streamer (ND5XS2 or NDX2) would be nice, as well as giving you a sound uplift, and potentially changing your view on the need for/choice of separate DAC.
Do you see your Royds as keepers? If they’re in good nick, and work in your room, you may be reluctant to change them, but maybe worth thinking about.
I am not sure I would describe it as the weakest link, but when I went from nd5xs to nds it brought back the loveliness that I had with the cds2 that preceded the nd5xs. So personally I would look there first (although I actually went from 180/102/napsc/hicap To 52/250/supercap before going from cds2 to nd5xs to nds)
Having recently auditioned a Qutest with and without M Scaler, of all the possible upgrade options, I would recommend a listen to what a Chord M Scaler can do to the performance of your system. I found it to provide a quite startling upgrade to the Chord Qutest.