Which is Better? Musical Fidelty A5 (used) or new Rogue Sphinx?

I currently have an NAD C 375 BEE integrated amp running a pair of BW 804S speakers. Have urge to get new integrated amp. Have considered a used Musical Fidelity A5 (it has lots of power) or a new Rogue Sphinx (not as much power but sweet sound). Listen mainly to classic rock and blues with some classic jazz and little classic country and western music. I also like it on the loud side. Can't decide. Which choice will give me the biggest upgrade over the NAD? I'm counting on some input from the membership.

Thanks