What equipment should I invest in next?

Demo  a Power Plant. You'll only be out shipping if you don't like it.

Very nice system as it stands! Get a cheap Schumann Generator.

First thought is that you are thinking in the right direction - cleaner power.
Regenerator or not, better power cables perhaps...
I use older PS Audio regenerator.
What does your turntable sit on ? Yeah, that's another direction - vibration control/tuning.
Put one half inch Walker Audio resonance control disc near your turntable motor, see what difference it will make. I heard slight but obvious improvement with my Nottingham. I got it directly from Walker for $50.
Perhaps another disc on top of SACD transport. This I don't know but I had the same effect as with turntable with the disc on top of Nakamichi deck.

Based on what you said, Townshend Podiums. I've used all kinds of power conditioners, power cords and cables. Good ones will definitely make a big improvement. But you know from first hand experience the unique timbre and tone of live instruments. What you are hearing right now, I'm sure it sounds very good but let's face it, you would never confuse it with a real live instrument in the room. Even my Moabs as dynamic as they are, we just don't get there.

But then even if we had the incredible dynamics of the real thing, we would still have the problem of the real thing starts and stops. The overtones and resonances we hear with a real instrument are produced by the instrument itself. The musician holds the instrument perfectly uncoupled from the floor. Piano and string bass, some drums, are among the few that couple to and excite the floor- and more and more pianists are discovering the improved sound of putting the piano on Pods! Search YouTube, watch the videos! 

Speakers on Podiums will do something for your music no conditioner can: restore truth of timbre! I have no doubt you will hear this immediately, and probably be surprised at how much instrumental uniqueness was hidden in those colorations.  

You have a very nice system that seems well-suited to your musical goals, which is more than I can say for many I've seen.  If you're looking for suggestions on how to bring out more of what you have, I have had success placing Symposium Svelte Shelves under my amp and dac.  It didn't change the sound, but lowered the noise floor and brought out a more realistic tone on acoustic instruments.  I at first tried placing the components directly on the shelves, which worked, but then tried Cardas wood footers under the dac and the Symposium metal feet under the amp, all of which worked well.  Which Morrow cables are you using? 

Synergistic Reaserch Orange Fuse 

for any useful advice, op, you should carefully and specifically articulate what are the perceived deficiencies of your current system, or, said differently, what traits you would like further improved

otherwise you will get just random ideas on how to piss away money based on other people’s experience and systems, not yours

as you know, your system is already first rate, so to get real improvements require careful thought and consideration

you may also want to post a picture of your room and setup

Ssmaudio, don't spend money on those things, they will add nothing.
You are a violinist. You really need to hear a pair of electrostatic speakers
like Sound Labs 545s or Sanders Sound Systems Model 10s. They will send chills up your spine. I love string quartets. I can listen to them for hours. They may have been the singular reason I fell in love with ESLs.
No other speaker I have heard puts the musicians in the room with you like these speakers. No other instrument has the complexity of tone and texture that a violin has. With ESLs you can easily pick out the differences in violins. As you know there are good ones then there are great ones. Some get worse as they age others get better. Save up and get a pair. I promise you will never look back.

Another good one, in addition to Townshend Podiums, since you have both digital and analog try some TA-102 fO.q tape. Find it on eBay for the best price. I got this from another guy here who uses it all over his turntable. Most vibration damping materials lower the noise floor but tend to suck the life and dynamics out of the instruments. This tape does not rob any dynamics but does remove a layer of detail obscuring grunge that has the counter-intuitive result of improving presence. The improvement with strings and wind instruments is impressive!  

Using this tape is a little more labor intensive because the stuff has to be cut to fit but it is super effective. I started with a piece just 1" by about 1/4" on my tone arm and even that small amount was noticeable. 

Study my system pics you will see I ran a strip along the underside of the arm tube, and underneath the arm base. Basically I keep it discrete yet effective. You would never see it in person unless you really go looking for it. The best is remove the cartridge and apply the tape to the head shell. Has to be cut and trimmed to fit. But when done holy smokes! Groove noise vanishes! Details pop out everywhere! From 1" of tape!  

Can also be used inside your DAC, transport, phono stage. Great around tubes. $50 for tape seems expensive until you use it all and hear how much improvement it makes, then it seems cheap for what you get.

+1 on the Podiums although you could also get great results with Stillpoints under your Tannoys. Think the$125 Ultra Minis would be ok.  Also agree that you have a really good system especially for a modest price!
A super strong recommendation is to get  a Silent Running Audio VR platform for your TT. They are custom made for your exact TT and are $1500. I got one for my TT and the improvement is unbelievable.
SRA makes these things for Medical and Military. Their upper line are the Ohio Class and Virginia Class since their technology is used in nuclear submarines! About the best $1500 I ever spent.

BTW-love the match of the J2 with the GRs!
Although you would also have a near perfect amp for Quad 57s.
The current best are Electrostatic Solutions (ESS). They use thicker Mylar and get bass out of the Quads that are unique. If you sold your GRs you would be significantly there for the ESS at $6500.
I lived, joyfully, with 57s for ten years and I miss them most every day. If you decide to Call Robin at Robyatt Audio and get a pair you will thank me. To this day, the best midrange in Audio! You will be floored by the sound of a violin, etc., etc.

Thanks all!  Lots to think about and digest.  I’ll ask follow ups as I do research and try out different things. 
BTW, although I appreciate the ESL suggestion, I’m not investing in any new speakers for another decade or so!  But I’ll still check them when the pandemic is over. 
BTW, got my second shot today. So am officially invincible now. 

Is your room optimized? Tonality even throughout? Clear, articulate, big-enough soundstage? Highs smooth? Bass taut? If any of these things are not true, then the thing to do is consider that a big part of the sound is due to your room. It's not sexy or fun to advise someone with great gear not to get other great gear or fancy tweaks or cables, but it's really worth considering if you might benefit from traps, absorbers, and/or diffusors.

@ssmaudio, 
 I'll echo the chorus, you have put together a very nice audio system. 
I bet the First Watt J2-Tannoy Kensington GR pairing is special. Agree with you, no need to change your speakers.

You're headed in the right direction in  considering improving AC power quality and addressing vibration and resonance management.  You simply can't go wrong with either step.
Best of luck, 
Charles 

@charles1dad and @mglik Thank you! I really do like the First Watt and the Tannoy. They really work well together. The FW really does have an analogue-ish sound with very little coloring. And the Tannoys really have the same quality plus the concentric drivers have a wide sweet spot and very good clarity. Perfect for classical and jazz. I do have an REL sub as well which complements them well.

This is my first real audiophile system and I didn’t want to spend a ton of money and am very happy with it. It’s the first time I have my own listening room (kids etc. till now that limited my disposable income and space). Although the system probably cost more than my son’s annual expenditure at Juilliard.

@hilde45, I do have Acoustic Geometry curve diffusers at reflection points and panel absorbers at strategic places in my room. I haven’t done exact measurements—I’m not an expert on that, but it’s probably good enough for government work.

@ssmaudio,
I’ll stray off topic momentarily, congratulations on your son’s acceptance to Juilliard,  that is some achievement. Is he studying violin? I studied trumpet in my youth but drifted away. Wish I’d stayed with it. You can’t keep me away from jazz clubs however😊.

Charles

Very comfortable listening chair.

(You seem to have the electronic part figured out already.)

@charles1dad he’s in grad school at Juilliard, yes in violin performance. Went to Oberlin Conservatory for his undergraduate. Main reason he went to OC was because he wanted to do a double degree in violin performance and computer science, but then on his fourth year decided to drop computer science. (I guess he’s just relegated to being another poor musician.)

Actually I’m pretty fortunate. His tuition etc is paid by scholarship, so we’re on the hook only for his apartment. Not bad really. Although I just realized that my expenditure on audio equipment is WAY more than Juilliard! Oh well. Best not to think about it.😂

@ssmaudio,
You are rightfully a very proud Papa😊.
I wish you son a bright and productive career in music.
Charles 

congrats ;-) great system, great son. i know a gal with a Strad, her system is nothing like yours....and it need not be....it is highly personal. i don’t know enough to help you....what is lacking ?

what is a particular reference that we might listen to ?

by the way, in my line of work ( retired ), government work was super high precision, hope your gps works well. ha.

enjoy your journey

jim

Perhaps upgrade the Morrow Audio cables, I tried them and thought they lacked detail, there’s better available around the same price range.

@tomic601  hi there,  thanks!  No offense meant with the government work. I have a lot of respect for the civil service and the scientists who work for the govt. My vaccine is one example.   Also my computer science research in grad school was funded by DARPA.  So have a lot for which to thank the bureaucrats. 

Two new tech products I have recently found transformational in my 50 years of trying near every damn thing, including MC's spring thingys. 

1) equipment and speaker supports from critical mass systems.  CS2 and LS2 respectively.

2)audiophile switches.  These clean and reclock your ethernet signal.  Three I know are Melco, SOTM and uptone audio's Ethernet Regen.  The last is the cheapest.  More than one in series is a further upgrade. I use three. 

Happy listening.

Townshend Podiums followed by power clean up.

That’s a pretty solid setup. Hard to
pick out any weak link. Used to own Kensington SE and now Canterbury GR - both wonderful speakers. I’m analog centric, so I’d ask whether you have that magnetic Concept arm. It’s very sensitive to feedback/footfalls. The Townshend speaker platforms will help but maybe also consider a platform for the table. And/or upgrade to a rigid bearing arm. Also look at upgrading the cartridge if you’re on the Concept MM. And if you have MC, an outboard SUT like a Bob’s Devices Sky is reputed to handily beat the ones inside the EAR 834. I have good power here so I don’t think I observed as much of a difference from power regen/conditioning as some do.

Thanks all. Question. How can I tell whether the power coming from my home electrical circuit is clean-ish or not?  Thanks!  Note that I’m not well versed in this area. 

Note that I’m not well versed in this area.

Understatement of the week. But that's not the dig. No one is. That's the dig.

Yes a better conditioner, power cords, outlets, etc etc will be better.

Very nice gear!  I've found that the First Watt amps respond well to a decent power cord. ( I run a J2,and an F5) The J2 is paired with an Anticables Level 3. I've noticed a wide,deep,and tall soundstage compared to a Zu,PS Audio cables I've been using.  YMMV. Enjoy the ride! 

Didn't mention your cartridge....I'd upgrade the phono stage.

You are asking the question... so clearly there is a problem. You are not glued to your listening chair with a big smile on your face. You know there is more. I reach plateaus... where I am just plain happy. So, I recommend being really introspective... what is missing? Is it rhythm and pace? Musicality? Or bass. Your components seem well matched. I will say that you have to put a lot of money into a Phonostage to have good one. But if your analog end sounds much better than your digital end then that could be it.

@ghdprentice , I’m actually quite happy with my outfit at the moment to be honest. It’s just there’s money burning a holler on my pockets as it’s wont to do, you know...

@ssmaudio - you might want to take a look at the following...

• Avantgarde Uno or Duo speakers
• Inakustik Cables - all of them

The Avantgarde are the best speaker I have heard to date, because they are extremely articulate and natural sounding - and I have been a Tannoy speaker fan for over 50 years, but the Duo’s were a whole new level of performance.

Inakustik are very good cables and would provide the dynamics and clarity the Avantgarde’s are designed to reproduce. They address almost all the issues of cable design using an outstanding cable geometry that promote clarity, dynamics, details, imaging and bass eprformance.

Just another opinion - Steve :-)