The Musical Fidelity A3 24 is very marginally better, and personally I liked the MF better overall compared to the Bel Canto, Chord and MSB dacs, fwiw. I sold the MF dac when I bought the Marants SA-14 as I felt I needed 100 more cd/sacds more then I needed a minor, though apparent, improvement in redbook playback (I can give specifics if you like). If you have the loot for a top notch dac, sure, you can surpass the redbook of the Marantz. The SA-14 makes for a great transport as well.
However, before adding a dac I'd spend time with isolation devices, power cables and interconnects. This is a very tweaky player, especially in terms of isolation, which will change it's character dramatically, more so then the addition of any of the above mentioned dacs ever would.