Sounds like you have pretty well matched set up as is. I've heard both your MuFi setup and the E.A.R. 834P with a cartridge in the performance category with the Lyra Dorian and didn't hear anything earthshakingly different as far as quality of sound. The E.A.R. is perhaps a bit more focused, but does not offer the tube sound.
If you plan on keeping the Dorian for the forseeable future, then my opinion would be to sit tight with the phono stage that you have.
If you plan on keeping the Dorian for the forseeable future, then my opinion would be to sit tight with the phono stage that you have.