It's no contest!!!...trust me. The separates will be stronger, more dynamic, more musical, more 3 dimmensional, better detail, and better everything sonically! Receivers are ok for small monitors with a sub, crossed over at around 50hz and above!..that's it. However, If you can do separates, I would do it EVERY TIME!!! No receiver is worth more than $2k personaly. The powersuplly's are inherantly weak in ALL RECIEVERS!..Including Denon 5800 and similar.
We once did a shootout of Denon's old flag ship AVR5600 (150wX5) and Yamaha DSPA3090 receivers, driving some little B&W 601 speakers, and some full range Mirage M3 speakers for giggles. The receivers were rather lackluster on their own. Then, we used the Receivers (both) as preamps, and added a llttle modest Denon 2 channel dedicated power amp(POA8200) to drive the speakers full range on music. WOW!...it was not even close! Infact the receivers were flat put to shame by the little 125w/ch Denon power amp! The receivers amp sections basically sucked in comparison. I mean EVERY aspect of the sound was bettered using the dedicated SEPARATES amp instead.
To this day, I have never heard ANY receiver that could compete with separates overall.
So, if you can spring...I would