the new D220 received!

[Confused]

maybe that's a thread in itself.

but yeah, I would agree mostly.
except that using the same speakers with the temporary replacement of my 250 (currently an ancient A&R A60 + DAC), there is no booming - albeit the sound doesn't reach anywhere near the bandwidth it does with the Dev.

So it could be that in addition to speaker + room combination, there may also be something in the way the amp handles those low (75 to 150Hz) frequencies that perhaps exaggerates the issue.

Why not reduce the SAM % below the 40% you are using?  Maybe to zero?  This still gives you the full phase and timing corrections that SAM offers, but will reduce the 'bass boost' aspect of SAM.

and yes, Devialet amps do seem to dig much deeper into the lowest bass than many other amps, so I can well imagine that the booming issue is kind of inadvertently reduced with your A&R amp.