I run a Shiraz and used to use 523e boards powered externally with HiCap, then went to Prefix which was ok, but was easily bettered in every area by an Artaxerxes X in DX2 case.
I believe Roksan have discontinued the Artaxerxes X and are designing a new phono stage, so it could be worth waiting for that.
I've never heard a Superline so can't comment.
mat
Bet the new one won't cost the 300 quid the Artaxerxes X plsu DSU currently costs!