I agree with Mikf, you are the customer and it your perception that counts.
However I upgraded from CVP605 to CVP805 some time back and I would certainly not change back.
To my ears all the sounds, sound better. Having said that, much of my playing is on headphones, but I believe the speaker system on the two models are identical.
As I’ve said elsewhere, the clarity and definition is what counts for me, like listening to FM radio after years of AM.
Maybe the 809 is somewhat better, I don’t know, could not afford it anyway😀