Next upgrade?

my two cents:

set up the REW and find out your room characteristics, you will see where to place your budget and time.

if the spectrum looks perfect, congrats. but still you can work on subsonic bandwidth which would make the sound change you may feel.

REW room eq wizard

"I like the system a lot..."

How long have you had it in it's current form?  Have you done anything to the space it's in?  What do you play on it that makes you want to fuss about with it?

Seems, as reubent comments, a 'solid system' as it stands...

What shortcomings seem to irk you?

(...just being the 'devils' advocate' tonight/this morning....because I can....;)....)

@sounasega

for other thoughts on how best to further upgrade i would encourage you to speak more about what you hear in the system today as it stands, what are its strengths and weaknesses as you hear the music, and what you would like to have improved via further attempts to upgrade the system

+1 on room treatments. 

@ghdprentice  makes many good points, as usual.  I also think you have a nice system and would enjoy it for a while, while working on room acoustics, inexpensive tweaks to assist even more. Like many, I think the Prima Luna is the strongest item right now.    Enjoy!