B&W Nautilus 803 or B&W 702 S2?

Thanks and I appreciate your food for thought. We do a lot of both digital and vinyl but I should also mention that this system doubles as our home theater. The Anthem A5 has been a concern of mine as well, I have my sights in on Mcintosh MC205 which I think will meet the needs from what I understand. What are your thoughts about 803s/804s or 803d/804d? I believe those are slightly newer? I will be auditioning 702 s2’s and CM series tomorrow, along with the rest of B&W line.

All the D series B&W's are more efficient than the older N and S models. One of my favorite systems I sold to a client of mine was the 802D2 on a ARC Ref75 which powered them just fine. I do agree somewhat with hifineubee that the S and N series B&W needed series power in order to make them really sing properly which is why I mentioned my choice of the 702 over the N803. Your current A5 will do just fine powering the 702. 

I was able to audition 804d3's today and they were very nice, but we also listened to Focal Kanta 2's and they were especially nice.  They also have a pair of Focal Electra 1038's that we were unable to audition, but from what the rep we telling us they are even better than the Kanta's...not sure though, from what I read Kanta's were replacing the Electa's.  Wondering how my Paradigm Reference Studio CC-570 V3 center would pair with either of these?

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.