Uneven soundstage help, please.

I've got a pair of ATC SCM40 v2's driven by a Musical Fidelity A308 (plenty of power) and overall I'm happy with this combination, given my budget, wife, and listening habits. My system is in an incredibly complex large room, with all sorts of variables in terms of reflection, absorption, etc. And these aren't exactly the same from one speaker to another. I have no choice about speaker placement, given the room configuration.
There's a phenomenon that concerns me, though, that I haven't been able to resolve. In order to get the center centered, I need to position the speakers and listening chair in such a way that the soundstage extends all the way to one speaker, but only three-quarters of the way to the other. It doesn't sound out of whack. It's just a narrower field than I had with my older KEF References, and I wonder if it would sound even better if this was resolved.
Has anyone else faced and solved this? What factors are driving it? I've been living with it comfortably, but I wonder.
Thanks ahead of time for any replies.
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