New speaker with imaging

Have you listened to the new B&W 800 series. I think the 803D retails for $8000. They sound fantastic. As good as your Matrix 804's are, they don't compare to the new ones.

You might look at the Vandersteen 3A's. Good luck.

It is my opinion that you would be far better off to look into speaker placement and room treatment before seeking to replace your speakers. If you feel that your room and placement are optimum, by all means then look for the better product.
I am a member of N.E.W.A.S. (Northeast Wisconsin Audiophile Society) and as such, have had the pleasure of visiting a number of different system setups of our other members. Some, I have been able to watch over a longer period of time. Within my own system as well as other member's system, I have heard major changes in sound just relating to placement of the speakers. I have listened to what some may call modest systems develop very good sound with great imaging, a well anchored soundstage, and an balanced frequency response, just through room treatment.
This experience is what prompts me to make the recommendation that I have. I can understand change. It is nice to have something new. I guess you will have to do what pleases you the most.

Vandersteen 3A Signatures would be my choice.

Will

For orchestral music try a line source or an electrostatic type speaker. Ones that come to mind are Martin Logan, Quad and Wisdom Audio. Depending on your price range.