Can my set up be improved?

[Jwg1749]

I have LS 50s, but have only tried them once with the Devialet.
As you write there could be a room mode being excited (25Hz with SAM, 40Hz without).
The fact that SAM can allow a LS50 to achieve these frequencies does not actually give them more or less power handling capability and they certainly still won't go as loud in the bass as bigger speakers.
It would surely be quite likely that the problem of playing loud bass heavy music with the LS50 and SAM is that the thermal and/or travel limits programmed in would be likely to be exceeded for the teensy mid/bass unit and SAM be in protection mode, no?

I was very impressed by the bass of my LS50s on full range orchestral music.

I agree entirely.

Part of the problem here is synthesized bass. In its extreme forms (which are actually fairly common in some styles of music) it's far removed from anything you get in classical music (except perhaps for some infrequent passages in organ music). So whilst the LS50s do very well with orchestral music, they may fall down (or be more liable to excite a room mode) with this synthesized stuff.