Not familiar with the details, but I think there was at least one video going around showing serious overvolting deforming/popping drivers which caused mass panic and confusion. I think the problem was fixed pretty soon afterwards.
As for 770 Pros, they work wonderfully well with my E17. Really low output impedance makes the bass nice and tight. I'm not sure what MLE tested on for his initial review but in that sense the Beyers could absolutely benefit from a decent amp, even though they might be easy to drive at a good volume from a Mixamp (or anything else)