You're unlikely to hear any improvement by replacing your electronics. The sonic improvements provided by changing electronics tend to be very subtle.
However, if you haven't already done so, be sure to run the receiver's Audyssey room equalization calibration: that'll make a significant improvement in sound quality.
Another major audio improvement could be noticed if you add a 10-12" subwoofer to your speaker configuration. Even the best floor-standing "full-range" speakers can't do justice to the low frequencies present in many games and action movies. Of course, if you're living in an apartment or other shared housing, your neighbors might object if you play loud or late at night. Low frequencies tend to travel easily through most construction materials, unlike the higher frequencies.
Marantz SR7009/7.1.4/FH+TM/DefTech PM1000/LCR+TM amped