Speaker upgrade for Primaluna EVO 300 - Looking to find some audio nirvana bliss!

I’ve had several speakers with Primaluna gear, to include Tannoy, Magico, Harbeth, YG acoustics, Revel, and Focal. The best synergy has been with the Focal Kanta range. These easily open up with a little power. The Kanta 2 used might be a little more than your $5k budget but are really nice with the PL. I have the Kanta 3s with EVO300 monos, and even one EVO300 in stereo does just fine with them.  Used YG acoustics Carmels are around $5k or under, and also worked very well with the PL gear.  They are very small towers, depending on your room one or the other speaker could be a better fit.  

I'll be a little iconoclastic here.  Have you thought of point source speakers?  They often image better.  The KEF LS 50 Meta is a pretty surprising speaker.  The wireless version drives the price up, but you already have amplification so don't need the W model.  With a good pair of stands (surprisingly important) you can still have enough left in your budget to pick up a quality sub.  Any floorstander under $5k is struggle a bit at the bottom and benefit from support anyway.  You don't need to blow the whole budget on the main speakers.  Just a thought

I have replaced my Rega RS5 speakers with Audio Physic Sitara 25's.  These are mostly driven by my Cayin CS55A, somewhat similar to the PL EVO 300, made in the same factory.  I use EL 34 tubes and the combination is very good with exceptional soundstage in a small, 4.5 x 3.2 m room. The Rega's were thin by comparison, with a tad more bass perhaps but neither as natural or as well integrated.  Mids are to die for and top end is clear, a little brighter but far more focussed. Any of the smaller AP floor standers go well with tubes in my experience.