Actually, I'm not trying to win. Honestly, there must have been something wrong with your preamp to mess up your soundstage to such a degree...as you describe it, you were almost listening in mono. Since you still have the pre you should plug it back in and check out that it is operating correctly before you sell it.
I have no doubt you are hearing improvements and that your new pre delivers the goods. What I'm questioning is, what was wrong with your prior preamp.