Xpantastic!

Hi all, curious if anyone has come across an issue where individual voice volumes on their xpander/M-12 are not the same? On my M-12, I have one voice in particular that is about 1dB quieter than the rest. It's not really noticeable in use, but was also just noticeable enough for me to become aware of it.

I should note that all of the voices are slightly different volumes when you actually start measuring them, but most are so close as to be a non-issue. If anything, it seems like one voice board (1-6) is slightly quieter than the other, but it passes on the VCA calibration (and everything else) so I'm wondering if it's maybe a parts tolerance thing that just hasn't gone out enough yet to cause the calibration to fail. I probably won't try and "fix" it for now, but it would be good to know in advance what the culprit might be. I.e., is this happening at the board level, or the voice level?