Depends on what area you would want to improve. I do not mean physically choosing a part, i mean what part of the sound quality could make you happiest to be better? If none, then LEAVE IT ALONE.
Say mabe more bass.. or better soundstaging, or more PRAT.
Whatever that sort of area.. THEN find out what tweaks and things can improve that area.
Blanket ideas of 'what next' are usually just shots into the darkness, unless you know what you are aiming at.