Interesting observation. I have a SLV-575UC I am currently futzing with so I have the service manual for this machine (which you can find online or get from Sams Photofact for $20). The manual does not show any kind of adjustment for calibrating the sharpness. The signal goes from the potentiometer on the front panel into the main video chip, no trimmers or the like in the path.
What happens if you turn the control to the right (clockwise)? Does the image ever improve closer to the Panasonic? How much usage has the Sony seen? It could be worn out or something out of whack.
It's also possible in the ten years since the Sony was made that Panasonic figured out how to make a better picture with cheaper hardware. Ten years is eternity in electronic development.
