Like the others who've already responded (NINaudio, TLS Guy & shadyJ), I also believe you have a good ear for speakers – you like KEF LS50s, and don't like the B&Ws you mentioned. I've heard LS50s in my home and got to compare them to speakers I have and know well. I think they're a good choice, especially if you have a smaller room. Expanding with more LS50s is not a bad idea.
In particular, I agree with NINaudio's suggestion about looking into Salk speakers. When I heard the LS50s, I thought they sounded roughly as good as
Salk SongSurround I speakers. They are among the least expensive speakers Salk makes. Because you mentioned liking "a speaker that 'disappears' and images and sound fields well" I think you would also like the
Philharmonic Audio BMR Monitor speakers. Both Salk and Philharmonic Audio speakers share the same designer who values the very sound qualities you like.
I also believe you're going about audio sensibly. You seem to realize that speakers are where the rubber hits the road. Many of those new to audio focus too much on the electronics and not the all important speakers. That said, you only briefly mentioned your NuPrime integrated amp. Is it the
NuPrime IDA-8? It's a 2-channel integrated amp, with 100 wpc class D output power, and a built-in DAC. I'm not interested in buying one, but we get plenty of new buyers who are interested in these or other new (non-traditional) models. What's your experience with it? And how did you come to know it?