Interestingly, I feel like the Aeolus leaks a lot more than my previous open-back cans (58X with Yaxi pads). If I do the whole hold-your-headphones-away-from-you-in-outstreched-hands thing (to determine if my listening levels are too loud - yeah, I know, super scientific), I feel like the music is really pretty audible even at low listening levels. Never had that experience with the 58Xs.
Could just be that the Yaxi-padded Senns were an exception to the rule, though. The pads made them insanely bassy and dark.