OK, did some listening, do this in a semi-review fashion:
Used my X3/Cardas LOD/ALO National.
Listened to my current obsessions (have badgered people here with mention/videos/links to these). These are: Fountains of Wayne (album Sky Full of Holes, tracks "Someone's Gonna Break Your Heart", "Action Hero" and "A Dip in the Ocean"); Valley Lodge, (album of the same name, tracks, "Every Little Thing" and "If It Takes All Night" and "All of my Loving"); and Caitlin Cary andThad Cockrell (album Begonias, track "Two Different Things". Also Bill Evans Trio, "Waltz for Debbie" from the album of the same name (a classic if there ever was one).
1)comfort/isolation-Sony by a mile, not that the HFA is bad, but my personal preference is for the deeper entry, better seal (for me) that I get from the Sony.
ma750 more sensitive, had to turn volume up a bit to equalize for the Sony, nothing major, though.
Isolation, as noted, was better for the Sony.
2)Sound-Highs:felt the 750 did favor highs a bit more than the Sony, but the Sony got the sound down more accurately. High hat, for instance, was more forceful, say, on the 750 on Waltz for Debbie, but sounded more like a real high hat on the Sonys. I seem to be alone on this, but I find the highs slightly "tizzy", not enough to be bothersome, but there, especially on comparison to the XBA-3.
Mids-felt they both did mids well, the Sony again seemed to give more "body" to the vocalist than the RHA.
Bass-once again, both had tuneful, full bass, felt the Sony had more body, more "bassiness" to the bass.
Soundstage-here the RHA was the winner, with a wider, more open soundstage than the Sony, and, relatedly, more open space between instruments.
They reminded me in some way of open vs closed back over ear phones, with the open giving much wider presentation, but the closed (at least the ones I'm experienced) having the edge in fullness/body of tone of instruments. (not so surprising as the Sony does isolate better).
I do really like both (but as I've said previously, I'm a headphone person, go for anything with 2 earpieces), but I'd likely reach for the Sony first. In fact, even though it stopped being FOTM a while back, I still have periodically pulled them out (when I'm not salivating over a new purchase). The Sony sounds a bit more like music to my ears; the 750 more "hi-fi". If your sonic preferences are different, you may feel otherwise.
