If you improve your room you will improve both systems. Have you acoustically measured and treated your room?
Next if you improve power you would improve both systems. Are you using an upgraded wall outlet and/or a power conditioner?
After taking care of these two I think getting the upgraded version of Audyssey ($199 at the Microsft store) and the calibrated mike for your denon would be astounding.
Finally, after doing all of the above you could look at either getting separates or new speakers.
See my virtual system for examples and before and after measurements.