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

If we could go into the details, assuming the same Avatar amp, what difference would I hear between same level ProAc, Tannoy, DeVore, Sonus Faber and AudioPhysics ? Going from $3500 to $5000 might be a possibility but I must be sure it is worth it.

Yeah, I remember I didn't like the sound of old Sonus Faber for the reasons that ghdprentice stated. I also thought they were sort of primitive sounding but this might've been because of the electronics they were used with.

I thought that Dynaudio required a lot of power to sound best, they are usually used with powerful transistor amp, I heard.

Same thing I bought. Magnepan 3.7

I have Maggie 1.7's actively crossed over to subs. HUGE difference getting the lows out of the Maggies. At $3500 you should be able to get the Maggie 3.7's with a full ribbon tweeter and a quality active crossover. After that you can add a pair of subs when funds accumulate. Rolling everything off at 60Hz with the 18db slope is nice however found 60Hz roll off on the low end at 18db/octave then the high end is set at 70Hz and 12db/octave

Maggies are notorious for soaking up power - op's tube amp is doing 60 Watts / ch on a good day (fairly optimistic for a push-pull pair of EL34).