You may have a serious mismatch of gear. What model Sony is this? Is it one of their ES models? Or one for $199? If the Pioneers are a quality model,made for high amplification,the Sony may not drive them very well.Or even the center for that matter. Also,what kind of signal source do you have(SAT,Dig cable,analog cable)? If you previously had fake surround,true DD may take a bit getting used to. Also,a stereo-only signal will play louder if the receiver is set to "5 CH Stereo",not one of the movie modes. If you only have analog cable you won't get DD surround.In that case you should leave the receiver set to "5 CH Stereo". Since most TV programs,analog or digital,are only in stereo anyway this is the mode I watch TV in the most. But play around with it. You might find that you like it another way.
HTIB's are able to be effective because the speakers & receiver are matched.They can provide a decent sound with only 20-30 watts per channel because of that.