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
