I have owned the 804S for 18months, upgraded to the 803D two months ago.
In comparison, for the 804S:
- smaller footprint and lower height more elegant for small/medium rooms.
- lean bass results in virtually no bass boom,
- surprisingly deep and articulate bass for relatively small loudspeaker
- more open neutral midrange (less of a dip in the presence zone)
On other hand, 803D is:
- deeper, fuller, has more tonal colour through bass
- seems easier to drive since not as much volume needed to get decent bass
- smoother transition and integration between drivers
- diamond tweeter smoother, more relaxed
I enjoyed the 804S open midrange but I could not live with the lean bass balance in the long-term. The 803D is a substantial improvement for me.
In comparison, for the 804S:
- smaller footprint and lower height more elegant for small/medium rooms.
- lean bass results in virtually no bass boom,
- surprisingly deep and articulate bass for relatively small loudspeaker
- more open neutral midrange (less of a dip in the presence zone)
On other hand, 803D is:
- deeper, fuller, has more tonal colour through bass
- seems easier to drive since not as much volume needed to get decent bass
- smoother transition and integration between drivers
- diamond tweeter smoother, more relaxed
I enjoyed the 804S open midrange but I could not live with the lean bass balance in the long-term. The 803D is a substantial improvement for me.