I'd add that "most" projects I get in, whether from pro OR project studios, have stereo imaging anomalies that I try to address even before tonal shaping. The stereo image is one of those things that a lot of "mastering" engineers (quotes used in sarcasm, referring to 'some guy with a PC and WaveLab' calling himself a "mastering" engineer) have no idea how to handle. There are no "mastering programs" (sarcastic quotes again...) that truly address the issue.
This is nothing new, as the mastering engineer's job always has included image management and enhancement. The hard part is the "feel" of panning - If you pan an
acoustic guitar all the way to the left, it sounds completely different from an acoustic guitarist sitting to your left. While certain stereo mic'ing techniques will make a "natural" sounding stereo image, the panning of a mono track is inherently flawed from the start.
For a more "zen" example of this, there's an article (Stereo Imaging) on my site and an audio example on the Audio Samples and Studies page (under "services" - look for Classical Contemporary - Schaumburg Youth Orchestra - The Typewriter) of a WAY exaggerated stereo image from a spaced pair recording with no "center" to speak of, A/B'd against the mastered version - The stereo image was adjusted to imitate what the listener would actually be more likely to hear at the podium. Instead of instruments on the left and instruments on the right, suddenly you can "point" to an instrument that's towards the center, yet the stereo image remains wide and bright.
It's still not the greatest recording in the world, but it certainly served its purpose for this particular study.
John Scrip -
www.massivemastering.com