I see that mastering engineers are able to improve imaging on mixes. I was wondering what methods are used to accomplish this goal. If I had to guess, I imagine reclocking would be helpful- right? I suppose jitter would be the enemy of excellent imaging. Although, what is foreign to me is how mastering engineers are able to improve the imaging while only working with the 2 channel mix.

How many of you guys use a stereo expander to obtain more clarity in mastering . and if you don't what other methods you use to clear up the two track stereo mix?