Most resolving Speaker

Charney Audio Concerto!

Rear loaded horn based on the Tractrix theory. The Concerto produces a clean clear picture into the recording venue and studio recordings have a live presence due to the amount of detail retrieved. Of course this is all dependent on the front end and associated electronics. Room tuning is necessary but only to a minimum with Charney Audio horns. If you can't swing the Concerto the Companion with Lowther DX65 or Voxativ AF 2.6 will do the same with a little less bass.

Quite easily a restored original ESL by Wayne Picquet 

I have actually found the general concept of "higher resolution speakers" to be somewhat overblown.

Once you get to a competent level of speaker design, not grossly colored so as to obscure parts of the spectrum, most speakers IMO produce most of the detail in the source. 

Like every audiophile I've had that experience of listening to a speaker - uber expensive or not - and thinking "wow, listen to that detail, I don't think I've ever heard that before on that track."

But when I actually listen to the same track on another competent speaker, or on my home system...well...there it is.  That oboe part in orchestra, that bell in the back of the hall, that finger picking strings...whatever...so long as it's within the frequency range of two different well designed speakers....I'll hear it.

Now, that doesn't mean that I think one speaker can not in principle or practice render "more" detail, or reduce distortion relative to another.  Of course that can be the case.  But in terms of perception I don't typically find the effect to be "hearing details or elements that I couldn't hear before" but rather on the presentation of details I can hear.  In other words, a tiny bell in the background or a sax in the foreground will be similarly audible, but it may sound more "pure" or grain-free, and in that sense more realistic. 

So for the most part, I don't hear "new things" in a "more resolving" speaker.  I hear all the same things...but presented somewhat differently (which can of course also occur due to frequency response variations and other aspects of a speaker).