Hello! It sounds like you’re quite the basshead compared to me…and there’s nothing wrong with that at all! :)
I wasn’t meaning to imply that the M100 is bad, just that it’s totally a basshead headphone. Even Tyll titled that article “A Basshead’s delight.” I think it has a nice sound, and I’ve had the chance to audition one several times, but it’s not something I personally want to own even though I love the build and design of it.
Have you considered any open headphones? They’ll provide more of the soundstage you’re looking for…but you might find their tendency towards increased treble fatiguing. Generally though, mid/high peaks and soundstage go hand in hand, because we discern positional cues better in higher frequency material.
The only open headphone I’ve ever personally really loved is the DT990, but again, that’s probably too treble-heavy for your tastes.
I like the HRM5 and the HRM6, and I think they’re both underrated and under-loved models. I don’t think either probably has quite the bass you’re looking for, but they are less peaky and fatiguing than the M50X.