Bookshelf Speakers with Rel 212se Subwoofer

@yoby , just this weekend I heard a pair of Dynaudio Heritage Special loudspeakers do a surprisingly excellent job of casting an image while sounding totally neutral. They reminded me of the LS3 5A but with more bass. They are within your price range. IMHE only Harbeth makes bookshelf speakers of that quality. Since you are using a subwoofer the Harbeth P3ESR XD is another option and less expensive. Do not let the small size of these speakers fool you. The Dynaudio has a ferro fluid cooled tweeter. With a subwoofer and a proper two way crossover they will play as loud as any large point source speaker.

Wolf von Langa SERENDIPITY.

@grinnell I have a small REL sub with my de Capos, crossover set pretty high. They blend seamlessly. 

Here's my recommendation: Revival Audio Atalante 3 monitors. 

All the best,
Nonoise

A used pair of Joseph Audio Pulsars are well within your budget and are all-around outstanding speakers that’ll let you cross over your sub at a lower frequency than many other monitors.  Fritz speakers also worth a look.  Best of luck.