Picking a speakers

I’m familiar with the 804Ns and their bass capabilities are not much to write home about, and especially since you’re using a sub I think you’d be giving up more in sound quality than improving bass/dynamics.  If you feel like upgrading the center it certainly can’t hurt but not sure you’ll get a big improvement as the designs are quite similar.  What’s the rest of the equipment in your system, and is your priority more 2 channel or HT?  Depending on this you may be better off putting those $$$ to work elsewhere in your system so definitely take that into consideration. 

I'm using it 50/50 music and movies. Denon receiver and Denon 2 ch amp, that I want to replace for another 3 ch amp eventually.

The main reason for upgrading to the 804s would be if you wanted a fuller, more bass heavy sound and to do a better job filling the room.  I find bookshelves tend to struggle with large rooms at higher volumes then their floorstanding counterparts. If the sub is sufficient delivering bass, and the speakers/amp don't sound constrained at your listening volumes then I'd stick with what you have.

@soix ​​​​@ghdprentice 

+1 

This daring duo nailed it ..AGAIN ….

Thank you. My room is 19'x11', but my speakers positioned on the 11' side, so I think it should be enough sound for me. Thank you so much for your time and help. I'm new to high end audio equipment, but I really love music and trying to figure out what would work best without breaking a budget.