Forum admiration and requested guidance

Boy, are you ever going to have fun! 

It is the two ends that will give you the largest improvement. The middle stuff is clean up and basically depends on what you do at the ends. 

First is speakers and the room. Going for speakers with more directional behavior will make the room easier to deal with, horns or dipoles. If you were a loud rocker I would go with something like Klipsch Cornwalls and subwoofers. If you were a quieter guy who liked a larger more lifelike stage I would go with Magneplanar 3.7i's and subwoofers. The Magneplanars will require a more powerful amp in the end but your A23 will hold the fort. The Cornwalls with tear your head off with the A23. You will need to find and deaden first reflection points which you can do with $30.00 worth of foam acoustic tiles. 

Next I would upgrade your turntable. A Sota Sapphire with a Schroder CB arm would fit. It is the least expensive stable fully isolated table made. I think you can add Vacuum clamping, a big plus. Always get the dust cover. I have a CB arm and am very pleased with it. It's only down side is it does not have an arm rest. Mr Schroder does not like hanging things off his arms, they resonate. I made a locking arm rest for my table and solved that issue. Otherwise the arm is brilliant. The Kuzma 4 Point 9 is a great arm and will also fot

@chakster , that is an interesting take on walls. I never thought about it that way. But if studded walls are not dampened wouldn't they keep going and pass the bass back into the room? Certainly, no walls is the best solution. The resonance of the wall will create a peak in the bass which can be handled partially by room control.  

It is academic as none of us have a choice other than to use 2 X 6 studs.
As far as I know nobody uses real masonry walls in the interior of residential homes and only on the exterior of large commercial buildings. The interior of these is aluminum studs which are way worse than wooden studs.

I was playing Soundgarden's Badmotorfinger yesterday at 95 dB. This record has some serious bass. They were using feedback in the low 20 Hz range. I went outside to grab some parsley out of the garden and happened to look up at the picture window adjacent to the left channel speaker. The sun was reflecting off it as it was doing this amazing dance. 
I wish I did not put a window there and I am seriously considering removing it.  

Nandric, some of us have priorities that exceed Hi Fi in importance. Once my kids hit school age we decided to send them to private school and my stereo hobby stalled out for at least 15 years until they graduated from college. Phillips Andover cost as much as most colleges. It is just now that I have started to make the upgrades I have been dreaming about for years.