Bookshelf Speakers with Rel 212se Subwoofer

There are many good book shelf speakers. Look for one that matches your amplification and source and cables. You have plenty of bass so if it were me I would want a speaker with a reach midrange. 

@sounds_real_audio : Did you mean "rich midrange"?

Look at Reference 3A de Capos

never tried them with a sub b/c they have enough bass for me but it would defintely extend the range.

What speakers do you have now, and what improvements/sound characteristics are you looking for?

I have a pair of ATC SCM19's and I just love them. Very tight and accurate, with great imaging and soundstage.

The frequency response rolls off below 58hz, but I am using a bass array so it wasn't an issue.