$3500 floor standing speakers used. What would be your choice ?

End of last year I bought a used pair of Eggleston works Andra speakers. Based on their sound I'm guessing any Eggleston works speakers (for what you're talking about you could go with a smaller speaker from them) would foot your bill. 

Definitely not bright and the mids are exquisite. (Bass is equally fantastic but that doesn't seem to be a driving force for you and more to the point I think likely their other speakers if you find something smaller than what I got will sound equally good in the mid\highs region) 

On a side note I'd not be afraid of keeping an older speaker if you love the sound you've got. I've got a pair of Wharfedale stand mount speakers I bought new somewhere around 1988 and they still sound great. And without question they've worked hard for many years lol. 

E.

everhard, appreciate your suggestion. I have not heard Andra but read about them. How they would work with my amp is something that I can't really know.

Yeah, I'll keep my current speakers in any case for as long as they can be kept operational. So far, as I upgrade amps and cables they sound better and better. In fact, they are very sensitive to even very minor changes, and I like this. the entire system is very tunable.

Fyne speakers are 8 ohms and efficient so should work great with your amp. They are designed by engineers who left Tannoy. Their SP models are very nice. 

Check out a pair of Usher DMD Diamond Two Floor Standing speakers, They are a very fine speaker 2.5 way, they are around 50" tall, have a curved back, biwired, with cast iron bases/stands and very nice wooden veneer sides in various finishes and play all types of music.

Aerial Acoustics, 10T - not easy to find, big & heavy but for $3-$3500 used, Mike Kelly's masterpiece is still an amazing system. 
https://www.stereophile.com/content/aerial-acoustics-10t-loudspeaker-page-3