Imo the elex is an upgrade from the sundara is most every way imo, it’s pretty sweet. The sundara is more neutral bright where the elex is a slight w, but they are both relatively neutral. I think the elex is more detailed, dynamic, on the same level of speed, and also has slightly better timbre. I also think the elex is more impressive for recreating a space for sure. I do actually slightly prefer the comfort on the sundara though. And the wire for the elex is pretty shite but it is replaceable