Hi audiotrek,
While I've never liked Sony AV receivers or even their ES line and never recommend them, it's highly unlikely (as JohnK has pointed out) that there would be a specific problem with the center channel.
Most cases of center-channel lack of clarity or intelligibility are because of placement problems and simply running the center too low in level. Lots of soundtrack mixing engineers get carried away with surround effects and do not mix the center channel loud enough (they've heard the dialog endless times while editing the movie or program and don't realize the dialog channel is too weak). Make sure your VP150 isn't "buried" in some entertainment center nook. Aim it towards your listening area by putting a rubber door stop under the back edge (or, if you're in Canada, a hockey puck. . .).
I often run my center 5 dB hotter than the rest of the speakers, particularly with certain programs (I just watched one of my favorites, "Law &Order: Criminal Intent," broadcast in Dolby Digital 5.1, and the surround mixes are so relatively loud (New York city ambience, etc.) that I always crank the center up to make the dialog intelligible.
I do the same for movies where dialog has been mixed too low-level.
Another factor may be that you're running your surrounds too loud. Many enthusiasts want to "hear" the surround channels as distinct entities (they should blend in and not call attention to themselves), which invariably means they're set too loud.
Regards,
Alan
