Best improvement for the buck


I just recently sold a McIntosh mc250 and now have about $900 to spend to improve my system. 
Parasound p5 
Parasound A21 +
Denon dp51f  with grado gold
Magnapan 1.7i 
Klipsch 10" sub on stand
Oppo bdp83 
Blue Jean interconnects 
Sony 8" sub on stand
Monoprice xlp interconnects 
DIY braided speaker cable. 
So now the question is what is the most logical improvement or improvements.any suggestions?
audiomaze
Why did you sell the MC250?  If you are spending just the 900, you can’t get the Parasound A21+.  That is a new amp that sells for $3000.00.  What was it about the MC250 you did not like?  What is the rest of your system?
Depending on who you ask the correct answer is "room treatments" or "sell all your gear and buy a Raven integrated and a pair of Tektons". 
If you are keeping your system as is, take a look at ADD-POWR

https://add-powr.com/about

have about $900 to spend to improve my system

When I was young, I'd place a penny on the head shell when it went over a skip on the record..... really!