To re-run MRC or not......?

In the last week or so we've fitted a new carpet with a much thicker underlay than previously. I expected it would require a re-run of MRC and with the new levels in the v6 a new calibration.

So, all seemed to work very well as usual.

Calibration showed rear channels coming in at 4-5dB lower than normal. I wonder if the new firmware changes the fronts vs rears?

New decay is 393 vs old of 352. 29 filters instead of 38 rebuilt at 300 target decay.

I don't think the new firmware updates cause any MRC changes, I suspect its all down to room change.

If anyone else recalibrates or re-runs MRC, I'd be interested to know if you see any changes.

Rgds,
Nick