My comparison with the RN6 for anyone interested
RN6 (red filter)
Thicker in the mid/low mid
Closer sounding overall, hence vocals more forward, instruments only slightly, in general
Feels a tad more congestionned, less airy on busy passages (less drivers could show here)
Can hit very hard too, tight attacks, good sub extensions (but sometimes on the verge of boomy)
Little depth but good soundstage, wide and not agressive (like some UM are borderline with that)
Slightly shouty on some tracks, otherwise great tonality
A bit more dynamic contrasts, can be enjoyable but makes it a more intense listening experience
Maestro (without any EQ)
Feels a bit more distant
Low mids just right, not thin or too thick, in comparison
Better vocals, more texture/micro details, yet smoother
Bass attack, slightly better, tigher but with even more sub than the RN6, not boomy but it's a lot imo
Some slight harshness on high frequency percusions (very track dependant and tips)
A bit narrower soundstage but sounds bigger, and i would say it could be more precise in that narrower space
I would have hard time picking a winner if it had to be only one at this point. With my little EQ plateau for the sub on the Maestro, i would give it the nod as it's the closest to my ideal presentation but it's entirely a preference more than fundamentaly better technicalities. Those are slight differences, they are a bit better at different things and as i previously mentionned surprisingly similar in the end. Maestro might be a more relaxed experience outside bass, everything is less forward, except the bass region.
I think equal amount of people would find more musical either one or the other. My personal bias is still the Maestro, it's how i would have tracks mixed and sound like, makes me dance in my head all the time... 2 fantastic sets regardless, can't go wrong with those and i still have to explore further the filters on the RN6 (they are so scaringly small to swap!). Although i forgot the RN6 is almost double the price than a MSE!
I should get the Canpur end of next week to compare. Final death match incoming.
Might go custom after that. I should also mention the RN6 is a smaller shell but i find it less comfortable of all the sets i have strangely, it's a hard shell and a bit more rough than typical resine shell, also more angular. I wonder even if it's the shell notch for the filter that is scratching my ear in some ways, i get soared after a while with them for some reasons. Also not a fan of the cable, it's a bit stiff and not super comfy near the ear hook area. Good side is there is less pressure building than the Maestro, due to the big vent. RN6 is super easy to drive, again in comparison to the MSE. Got caught a few times swapping them on the headamp with too much level for the Maestro...(about double)
ps: wrote way more than planned