Hi, not too sure how to advice you. Your demo journey has far exceeded the original price range of what you're looking for. When you hit $10k range, those speakers tend to be super picky with what gear you're pairing with, break in time, speaker cable used, music source...etc. Listening to my 805D3, different recordings of the same song sound significantly different. Try listening to old vinyl, vs 44khz CD, vs DSD vs complete remastered 192khz FLAC and you'll see. Without a good grasp of what your true budget range is, give your existing gear budget range, it would be very unwise to use such high end speakers for both music and hifi listening purpose. Most typical AV receiver are all unable to properly power such speakers. Most cannot do 4ohm let alone less than 4ohm. Your resulting experience will be very lean sound. Otherwise, you'll need to shell out a lot of money to add a secondary amp(s) to power your large speakers besides using AV receiver. Then you'll have all the other components to add.
As for the other B&W speakers, they're all very different. 803D is a lot bigger in size than 803S. D1/D2 has diamond tweeters vs S's aluminum tweeters. While both D and S line have kelvar woofers (the yellow cone), they are also tuned to have different sonic signatures (though not obvious unless you've owned them all like myself, I started with 805N). In general, I can say from personal experience, diamond tweeters are not the wow thing their price would suggestion. Better yes, but not 10x different as reflected in replacement parts cost. In general, each B&W 800 series generation loses warmth, become more neutral and more high resolution sensitive. Based on demo experience, the new continuum woofers used in 800 series D3 and 700 series S2 pair very well with Mcintosh amps. I will also add that personally I don't think neutral is a good thing, when today's new speakers, amp, cables, DAC are all 'neutral', what you get is the most blend sound ever, like eating organic salad with no flavoring or dressing. So beware.
