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
"When I was young, I'd place a penny on the head shell when it went over a skip on the record..... really!"
I did the same except it was not a penny. As time wore the record out, and time is money and vice versa, I started putting bigger coins to accomodate bigger and bigger skips.

The difference from then is that I am still young, if not younger.
Audiomaze,

I can't comment on the swarm which is a specific model of bass array, but conceptually bass arrays are much easier to integrate into most listening rooms versus, well almost anything else. If you have the money and space, you can use room treatment, but doing it right, it not easy, and taming deep bass requires large structures or good/lucky use of harmonic traps.  If you have a lot of flexibility in placement, very good results are possible with 2, but 4 is going to allow more flexible placement. Careful with subs near mains. If the swarm has reasonable bass management and they are low distortion so you don't get false images, then I would expect they will work well.
Those Blue Jean interconnects will throttle anything you put through them. I speak from experience.