B/W 702 s3

There is my room.  That took me a awhile.  Cool post image site.  Thanks

I see both (1) room issues (both sidewalls need absorption-drapes?-to tame reflections) and (2) speaker placement issues (perhaps depth perception of photo but appears speakers are very far away from listening position vs how far apart they are and they seem too close to front wall).  I agree with others that there may be a synergy issue with the  Rotel although it seems powerful enough to drive them.  Experiment with placement/room treatment first--yes, subs can help but those speakers have enough bottom for most music--someone also mentioned REW--you can also download the Audiotools app on your phone and use your phone mic to walk around your room using the acoustical analysis tools to see where your room modes and nulls are--it's close enough to REW and you don't need to purchase a mic.  

B&Ws need high current amplification. You don’t need to bi-amp them with rotels. You need a high quality amp, good cables and some acoustic treatment. Look into Coda amplifiers. They’re high current design. Coda No.8 should be good. 
I would also recommend limited range bass traps in the corners behind the speakers. GIK Acoustics makes good limited range tri traps. This would help improve bass definition. These are good speakers that simply need a good amp. 

Looking at the specs for the Rotel, it doubles wattage into 4 ohms which is one of the hallmarks of a high current amp--I've often seen B&W paired with Rotel without any issue and often very musical.  I still think it's the room/placement