twopecker,

At what volume level do you watch? I mean, once you calibrate the channels exactly as instructed by the receiver's manual, the "dB" numbers on the main volume knob (if the numbers are in dB scale) should correspond to +/- dB from the Dolby/THX "reference" level. Do you watch at -20dB, -10dB, or what?

Also, just in case, put your ears to each of the drivers on your VP150 to make sure all drivers are working. One disconnected tweeter would fully explain your symptom.