I dont think its your speakers necessarily. I have monitor 60's and a CS1 ran off an older denon 1611 in my bedroom and rarely turn the volume up beyond -25 or so, its is usually in the -30db range and have never experienced dialog intelligibility problems regardless of source - dish, blu-ray, dvd, ps3, netflix etc...all sound fine when it comes to dialog and action FX blending together. I use the denons audysey calibration and run the 60's full range (no sub) and an 80Hz crossover on the center which is set to small. the polk monitor series are far from high end - but they can sound pretty good when set up right - in my experience.
I am not very familiar with pioneer receivers so i cant be much help in diagnosing settings, but how is your center channel placed?....a picture is worth a thousand words here.
I don't need snobs to tell me how to think, thank you!