AV receiver recommendations for a 3.1 home cinema

[War1ock]

Hey everyone,
first time venturing into the world of true sound, which I know very little about so I'm hoping you guys can shed some light.
I'm building a 3.1 home cinema setup and currently I've got everything but the AV receiver.

• 1x sub: Klipsch Reference R-100SW
• 1x center speaker: Klipsch Reference R-52C
• 2x front speakers: Klipsch R-41M
• TV: SONY KD65XF9005B

The main objective is to being able to watch movies in 4K. I'm based in EU so I'm able to buy from all Amazons except the .com one, as well as other EU sites. The budget is up to 600€. This is how my setup currently looks like and I was planning on putting the AV underneath the center speaker within the furniture (not sure what's it called in english), which is 15.1cm high and like 50cm wide. (Originally I was planning on getting a Sony STR-DH590 which fits perfectly, but people recommended to get something better...) If you have recommendation that wouldn't fit there fine as well. Thanks a lot in advance!