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

mulveling,

I see. I agree, coherence is very important, single driver speaker without flaws is an almost unachievable goal.

Yes, choosing Tannoy would be a very complicated matter, especially if you can't audition them. I also understand that the better ones will go over $5k used .

@inna 

Given the limited amount of power you have on tap, would a good pair of bookshelf speakers paired with powered subwoofers make sense in your environment?

That would make things more complicated and probably more expensive. Integrating subwoofers can be a challenge. I like coherence. But theoretically yes, I have enough room for that.

60 good tube watts is not little at all for a medium size room. The amp sounds quite powerful with the current speakers.

A few years ago, based simply on the many glowing reviews, I bought a lightly used, $17K pair of bird's eye maple GamuT L7 speakers for $4K. Powered by a pair of Pass Labs XA-160.5 amps. I'm very happy with my purchase. The tough part is that I've only seen one other pair come up for sale since then. Good luck and happy listening!