Another vote on keeping the M22s and add a sub when your budget allows. Pretty much any bookshelf speaker is limited on lower fq's due to cabinet volume, the 22's are by all accounts, similar to Axioms tower speakers when combined with a half decent sub.

BTW, absolutely nothing wrong with your choice of receivers, Denons are the favourite choice here, for the most part.

Half of communication is listening. You can't listen with your mouth.