Saturn,
I have the exact same problem, however my soundstage is a bit off to the left. I also have M22Ti's, on SBF20 stands. I have compared this with my M3's in another and my Grado headphones, and yes, the soundstage is definitely off to the left. I swapped the M22's and the difference was still there.
The reason for this discrepancy is the room they are in. There is an opening on the right, so more sound is escaping throught it rather than bouncing off a wall and back to the listening position. I have since put my left channel at -1 and my right channel at +1, and the sound is more centered, although not perfect. It will become perfect when I have a perfect listening room!
