What is this speaker doing right?

I don’t have a CD player. Tidal or vinyl in my two systems only. 

The LS50 FR spec of 79-28kHz +/-3dB is somewhat misleading because it's done under anechoic conditions with no port output. With port output included, Stereophile  measurements show a flat bass response down to 50Hz. The Sound & Vision review also indicates a measured FR of 46-20kHz +/-3.2dB. 

Could be the tidal. Try cd.

Interesting mikapen!  I don’t know anything about phase alignment. 

I haven't heard your Wharfedales, so I don't have a comment.
However, despite their oft-repeated phase alignment claims, I hear significant phase shift distortion from the KEF's.
Results in discomfort, listener fatigue, and desire to turn them down. Kind of like a Bose 901.

I have a pair of these for a bedroom system powered by an NAD C326BEE and C516BEE CD player. They offer a relaxed yet detailed soundstage that is very musical. Wished I had this good a system back in college. Great speakers regardless of price.

Really interesting post.  I too have a pair of Wharfedale Denton 80th Anniversary speakers running Bluesound (Tidal) in my basement "man-cave".  I'm continually shocked by how good they sound as I run through some "retro" equipment - a Marantz 170DC amp and Luxman CL-350 preamp.  I've always attributed the sweet sound mainly to the room acoustics but maybe I should be giving the speakers a bit more credit!

Twoleafers 

I think that t is well said. The KEFs sound pristine and modern. I can not fault them. They are great speakers. It is just that I’m enjoying the body and charm of the Dentons. 

Look at all the nearly unanimous praise heaped on the LS50's.  It's the epitome of what I've come to call the "modern sound".  Some of us are coming to the conclusion that older models (or older designs) with a different design or design goals, sound better to our ears, whatever better means.

Well it’s the next day and I’m still enjoying the Dentons more. 

You are right that the tweeter is smooth. The speaker is also less fussy with placement. It’s very musical. While the KEF is more analytical and accurate, the Dentons are more enjoyable to me. 

For claification, the euphonic description referred to my tube system driving PSB imagine t2s in a dedicated room—not the KEFs. 

The LS50s are a great speaker. But if I had to live with one I’d take the Dentons in my room with my setup.  

And for for the record I would recommend the KEFs to others.  I’d also say folks should be snatching up Dentons for second systems as they are a great value, well made and sound delicious.  

Or, the Dentons are in fact better to your ears. Perhaps not set up optimally, but it doesn't surprise me that you are enjoying them so much. 

Welcome to variety in speakers. The LS50 is 79Hz +/-3dB. Bass MIA.  I would not tolerate that much of the music/bass lost in my home, unless there was a subwoofer with them. I do not care how pretty the rest of the spectrum is, if you drop fundamental low end you're not doing justice to the music. It's easy to sense that things are separated when there is little bass. 

The Denton is at 44Hz +/3dB. Welcome back bass! Imo, what you seem to be calling "phony mid-bass warmth" is actually a part of the music the LS50 drops entirely. I can see perfectly why the Denton is more enjoyable in some respects. I remember way back I had a Rogers small bookshelf, a very engaging small speaker. Though I have not heard it the Denton strikes me similarly. I reviewed some speakers in the Wharfedale Opus line, and they were also very engaging. 

Perhaps you mean "coherent" rather than euphonic describing the LS50, because your reaction to the Denton shows that it is tremendously euphonic to you. 

These are two very different flavors of experience in small packages. For the fun of it try the Wharfedale speakers upside down, and with tweeter to outside, then inside, to see what you think of that. Easy, free variety. 

Wharferdale uses really smooth and low compression tweeters and don't get  enough credit for it. 

You may change your mind tomorrow!