The 875
1) adds Reon HQV scaling
2) can upconvert analogue video inputs to 1080p, not the 576p of the 805
3) has bridgeable amplifier pairs as well as the 805's biamp capability
4) has three-zone AV operation rather than audio-only on the 805
5) has an extra HDMI input, making 4 in total
6) delivers 200w per channel output rather than the 805's 180w