I'm considering adding an external amp(3 channel)...I have a Denon AVR-3808CI and just upgraded to Aperion Grand Verus tower front Lt./Rt. and center speakers.
gjgonick,
Not trying to talk you out of the amp, but I had a similar experience. I had a Denon X4000, (125wpc compared to your 130wpc). I also had Aperion Verus Grand towers and center. In fact, I had 4x towers and used them for L/R and Surround L/R. (Had KEFs for rear surrounds to make my 7.2 system).
Read a lot about separate amps, had the bug and the money, so bought an Emotiva XPA5 w/ 200wpc. Powered L/R, Center and Surround L/R with it. Only used Denon to power the rear surrounds.
If I'm honest, I cannot unequivocally say the amp yielded any improvement. Maybe. I don't listen real loud except for big bing/bang/boom movies. Still, the Denon did that all by itself.
Naturally, I told my wife the sound was much more clear and detailed, likely even alluded to that fact here, and told myself it was true. But it was not until I upgraded my speakers that I REALLY noticed a difference.
Would I add the amp again? Yep. Can I say you will notice a difference? Nope. It was worth the $ to be really sure I had enough power... just don't expect a significant difference in your sound.