I am enjoying my analog system, but what can I do to improve?

But reduced bass extension might not be noticeable in your small room. You started this thread by asking for more “realism”. The road to realism does not run through reducing dynamics. The essence of live music vs any home audio system is the incredible dynamics of the live experience.

@lewm, what is happening is that loud passages sound too loud, so I turn the volume down. When I do that, quieter passages are too recessed.

I don’t have the experience and knowledge of those who have been advising you, but I know ‘too much gain’ when I hear you describe it. I’m in the camp of, ‘the speakers aren’t the problem’ — the amplification is. From what limited experience I do have, I can tell you that getting a cartridge level signal up to the point that a power amp can use it is a non-trivial process. I’m sitting in a 10’ x 10’ room myself, so I know what you’re dealing with. It is a near field listening situation. The dipole speaker needs a good distance behind it; but I agree with the fellow who wrote that is what a ‘live’ experience is all about. I would listen to the recommendations of those with experience in the electronics (I.e., the fellow who recommended the Pass Labs solution, or similar), that is, several comments have focused on a ‘mismatch’ between your turntable and your amp. You have budgeted 7k, surely you can improve that end of things before you ditch those wonderful speakers. 
 

Just my thoughts, for what it’s worth. 
 

By-the-way, I’m enjoying vintage Warfedale W70E speakers in my 10 x 10 space (15” woofer + 5-1/2” midrange + 1” Mylar tweeter fed by a Rogue Audio tube amp, controlled by a McIntosh C100 preamp). I have discovered that the preamp’s MM phono stage out-performs my ELAC Alchemy PPA-2 phono stage. From which I conclude that ‘synergy’ is something that manufacturers as well as users seek. 
 

Bottom line, I think you find yourself at a point that many of us audiophiles can identify with. It’s time for a rethink. Do you start at the source, or the speakers? Judging from the comments so far, I would start from the source. I agree wholeheartedly with the fellow who counseled trying a new turntable (if it comes to that) vs. replacing the arm, cartridge, etc. But getting from the cartridge to the amp sounds to me, again, judging from the comments so far, is where you should focus your energy (and money) first. From all reports, you have some awesome speakers and an amp capable of driving them. 
 

The other course of action counseled switching to a single-ended triode tube amp, but then it may well not drive those speakers, or may not be appropriate for the music you prefer to listen to, although I do believe that setup may well be appropriate for your room. It is something to consider as an alternative. 
 

I hope my thoughts help your deliberative process.  

I apparently do not understand the term 'dynamics' where it pertains to speakers if Quad ESL's lack dynamics. To me, the term dynamics means whether the music is played from ppp pianissimo to a triple forte. If I were to listen to Andras Schiff play a Beethoven Sonata and if I had the piano score to follow along, the dynamics through my Quad 2905's would be right on. So I would vote for the Quad 57's given their richness and life like sound but yes, they do lack where it pertains to the lower frequencies. And, I wouldn't advocate timing up a sub woofer with the 57's unless it was modified by somebody who really knows how to make it sound cohesive. This would typically mean incorporateng lower frequency mylar panels.

@rauliruegas , The combination of the head shell and the jack assembly will never be as light with less inertia as a fixed head. If there were no penalty for removable head shells then every one would have them. The best compromise I think is the Kuzma version. It still requires a heavy steel grub screw to lock the head shell in. SME moved away from removable head shells decades ago. Their best arms continue to have fixed shells and I know you like the SME V series as I do. It is a pity you can't get them any more without buying one of their tables. Hope they reverse that decision.