Dedicated Vinyl system next upgrade?

Great we are at the same page. :)

My journey in my dedicated symmetrical 2ch listening room. I got some treatment but far from enough. Even then I had that peek in that room at 73 dB still after many, many different listening positions and speaker placements. 

What I could do is to sound treat and target that 73 hz with Helmholtz or membrane absorbers that need to be tuned to 73 hz..

As we know a DSP will easily take down a peek. 

So best bang (sound quality) for the buck.
The Helmholtz or membrane vs DSP:
DSP will "treat" all frequencies not just one.
DSP will be cheaper
DSP will hit that target issue with greater precision.
DSP can give me 6/12/24/48 dB x-over between my sub and bookshelf speakers.
DSP can compensate for our physical hearing capability (Equal-loudness contour) + "house curves"
And so on..

So it were a no brainier for me to go with the DSP.

And I can now enjoy my HiFi even more with better sound quality despite that I have "degraded" the analog signal with a AD and DA conversion. :)

Room?

Yes exactly what I mean.
The biggest "component" in your system. ;)

What to upgrade is the question.

The upgrade Itch.. 
I am thinking like this.. You have a stereo setup in a room. Changing/upgrading a component here or there gives you maybe a better sound or different. Give or take some % in improved sound quality. 

Your room is a component that is not coincided that much and now we are talking about much bigger improvements to gain. Some say 30% to 50% of the system sound quality is from the component "room"..

So if you  are seriously searching for better sound quality start with the bigest component the room.

Every dedicated listening room that I have measured has issues. Period. And nobody can as a measuring system say "Oh I hear a peek at 73 hz of 27 dB" yes nobody knows that before but with measuring we know. (Measuring is knowing)

So do not go into that rabbit hole that is a lifelong swapping out component X and Y and repeat. Into the same and lousy sounding room. (Remember you do not know how bad it is when you haven't measured it)

When you measure and fix your room THEN it is the first time you truly hear your gear and get full return of your investment!

So what to buy? Then I suggest a calibrated measurement microphone less than 100$ and install free software REW. Invest time to learn how to measure and how and what room treatment does and so on. Learn where your listening space issues are. And deal with them.

This is the hard way to go, to force you to learn new things. It is SO much easier to swap a cord or place some vibration damper here or there. And most of us do that our whole life because we are lacy. But we will also never fully be able to hear our components full capability.

(As a side note when we have done what we think is a appropriate level of room treatment then it is time to look at DSP/Dirac and those type of "room corrections". 
I love my vinyl system but analog purists do not know what they talk about. They have a obsession that it should be 100% analog all the way. I have done exactly that journey.
We have so much more to gain in % of sound quality than the small loss of sound quality we get from converting to digital and do sound processing and then convert back to analog! 
Just that type of thinking is holding many audiophiles back from hearing better sound quality from their all analog setups! Again we are lacy and have come up with a false logical conclusion "all analog regime" and then we do not need to learn new stuff like room acoustics..)

My question is - what should I consider upgrading next? Should I ditch the integrated amp considering I’m using an external phono stage? Or should I go with a better integrated amp? Or should I look at a better cartridge? Do I upgrade my turntable or just the tonearm? Do I upgrade the power cable on my amp?
Here’s what I’m currently working with - and thanks for your thoughts/suggestions!

He asked for thoughts/suggestions..

Yes you are right. He only rambling on about components and gear.. And I felt that he is missing the greatest one of them all as I wrote. Just trying to help regarding what is the lowest hanging fruit to achieve better sound quality. 

Regarding tonearm.
If/when try to get one there you can get added functionality. Otherwise you get just the same and probably only little better in some regards.

One added functionality that will generate better sound quality is if you can get one with the ability to adjust the VTA (SRA) on the fly  during playback. Yes we can always do it manually back and forth with a less of a success. So do a tone arm swap that counts.

Another alternate is to get a tone arm that you could in the future could add maybe a "Easy VTA" to it at a later time.

 Anyway good luck with your upgrades. :)

@paulgardner
NP thanks for the clarification. Then we know that you have reached your maximum of treatment as I said before. ;)

Then it is time to measure and identify issues and solve them with a little DSP in the signal path between preamplifier and power amp/s. With that solution you do not need to put any sound treatment anywhere.
Benefits:

• Better integration between sub/s and speakers by:
• > by be able to compensate distance/time difference between sub/s speakers.
• > by be able to use Lindquist steeper x-over filter that he also advocate for.
• Adjust the unlinear frequency response of your speakers (all speakers has that more or less) or maybe there is a dip that you like.
• Adjust for unlinear frequency response how your room interact with your speakers.
• Being able to adjust for "Equal-loudness contour" (Fletcher-Munson curves or international standard ISO 226:2003)
• Being able to adjust for your own preferred sound preference.

Probably something that i have forgot..

Regarding the integration between sub and speakers.. I am able to turn off my bookshelf speakers. And only listening to the subwoofer. I got very surprised when I could hear faint in the background when the subwoofer were playing the sound of the singer and other instruments that is higher in the frequency range..
And the cut of frequency were at the lowest setting at 40 hz!
I should not be able to hear a singer at all. I suppose the implementation of the knob on my subwoofer were using a shallow x-over slope perhaps max 6 dB/octave.
But with the DSP doing its job and I use 48 dB/octave at 53 Hz. Now the problem is solved with that the subwoofer will only amplifie and play those frequencies it should and nothing else.

mijostyn. It is good that you like your setup regime of SRA. There is always room for improvements.

For me is that a suboptimal procedure and explains why you do not put that much care in my opinion to it that it may deserve.

Don't get me wrong I also have a USB microscope laying around. The SRA regime you use I call it for the Michael Fremer method.

I am more in the Peter Ledermann camp of method. There we adjust the SRA during when the record is playing. There is a difference between when like Michael F put down the stylus at stand still in stasis.
If you adjust to 92° at stand still and then when you are done, play a record that will put friction and grove modulation on the stylus then you will no longer have 92°.

The dynamic adjustment that Peter L is using is then to do the final fine adjustments by ear.
Now there will a micrometer precision instrument come handy when adjusting the tone arm height on the fly, while you play the record. There is information online on what to listen after and what albums and track to use.

During my years of study how the best do their setups I have learned that there is usually several ways how to go about for adjusting each setting/parameter on a TT.  
 
So that is why I believe that making sure that the stylus is in the groove with all the parameters as close to ideal is more important for sound quality then what tone arm it is. If the angles between the stylus and grove is little bit more "off". The tone arm cannot compensate for that.

And yes the ideal SRA is changing with different records but the ball is on the playing field and not somewhere in the arena. And on the other hand that is then easily adjusted if we want/needed.

@miostyn that is great!
Yes that is WHY we need or the great benefit with being able to adjust VTA while you play the record! (On the fly) because as you say our audio memory is not that long..

For example this after market tone arm can do that party trick: :)
Stogi S 12 VTA
Or
https://www.analogplanet.com/content/kuzma-stogi-s-se-12-tonearm-vta-tower-serious-overachiever