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
I would start with your amp/preamp combo and go from there. Move to source improvements afterward.

Oz



IMO a mediocre horn speaker at $900 new or used would not improve his system, since that is what the OP is after.. A properly set up Magnepan 1.7i rivals box speakers costing ??? you know the rest!
The point of variety is variety. 
Horn speaker was an example. 
Maggie's are all that to some. To others like myself they are just a flavor.
I had the P5, it’s no match for the A21+. The P6 doesn’t seem like a huge improvement, though a bunch of minor improvements could be worthwhile


Whatever preamp you chose, make sure it is True Balanced and connect the amp/pre with high quality XLR cable: I use WireWorld

hth
It looks like the cable upgrade seems to be the way to go. At least a start.  Thank you all.