I really enjoy dxm too but the tolerance definitely lingers. I’m not sure if it’s all dissos, as I don’t have access to any other regularly but iirc nmda tolerance in general seems to Be quite persistent (admittedly I’m not sure why).
These days I try to keep my dosing of dxm spaced well apart as even dosing once a month really seems to dull the magic - in a way, like mdma.
Personally I enjoy dosing lower, for me, and adding a modest amount of psychedelic - trypts and lysergamides mix well, edibles too. It really seems to rig out the best of both.
I’ve never combined dxm with phens as Ive never tried mescalogues and I Couldn’t imagine the body load from 2cs meshing well with that from dxm