Primare i21 vs. Yamaha A-S2000

I'm currently using Totem Model 1 Signature speakers + Primare i21 amp + Rega Apollo CDP.
I'm thinking about replacing the amp with Yamaha A-S2000 while keeping the speakers and the CDP. However, I'm not really sure if replacing the amp will improve sound quality or not.
What do you guys think?
Is there something you dont like about the i21? If not the Primare i31 is a nice upgrade(dual mono).