Sorry guys, getting back to it:
RO3- Smooth, need more treble energy, but they're not fatiguing. Because of the increase in midbass, Robin's bassline on Lorelei is more prevalent. There's still an echo/reverb in the bass (boomy) that takes away from the clarity. We come to the fast parts on the Shining track, once again, has trouble with the speed. It's like the bass speaker takes too much time to recover, a "loose bass" sound without that exactly. There's a fairly decent depth to these phones, just not a good width.
ma750- From the outset these are my FOTM. Clarity there, treble response, soundstage and separation. The transparency is really striking on these. I would call these neutral to bright. Much has been made about the cable on these, and I've read some compare it to the RO3. Other than color and visual cues they really aren't that similar. THe cable on the ma750 is less microphonic, the lower cable is more pliable, the ma750 has a straight connector opposed to the 45 degree of the RO3. The most striking difference is the memory wire portion. The ma750 is more pliable, definitely less microphonic at the memory wire portion and is more comfortable. I'm not sure how the ma750 does it, but there's a transparency between Elizabeths vocals and the cymbals that are almost the same frequencies. It somehow mutes that response and brings the vocals forward. The separation for the panning clicks of the electronic percussion are pushed out to the edges and aid to the surrounding but live feeling. Because of the increased treble response the strings in Shining are more alive, biting,real.Guitars have more attack. Broken glass sounds like broken glass. Still enough bass to support the monster double bass rumble in the background. Fast enough to handle this track. You can clearly hear the two vocal tracks.Then it drops to the acoustic portion, this is where dynamics really shine IMO. Timbre. Cymbals just don't have that decay on an armature. The tonal differences on percussion elements very apparent with these, cymbal differences, position, depth.The buzz of the frets, scrape of the fingers, shimmer of the ride, snap of the snare. Trespassers William really have good separation on these. Vocals front and center.The throat tickle is back. The soundstage depth and width really helps these IEM's.
So in summary, these all of course depend upon your needs and tastes. Fit issues, preferences, length of time wearing etc all play factors. Believe me I understand.
I'd call the im50/RO3 about even, it depends upon what you're wanting. Sub-bass and treble energy more on Im50, midbass and less bright on the RO3.
I wouldn't take the crystals over these, but they're about equal depending on v/non v preferences. But if you hate over the ear, there's that too.
For balance/fit/comfort etc I'd get the ma750 or SM1. SM1 wins for isolation and microphonics, but not by a mile. For my money neither is disappointing, but my lean is towards the ma750 with 3 year (!) warranty and the great spaciousness, imaging and transparency. Warmer than an Etymotic.
So much for it being an R03 review. I think they're a pretty decent IEM, depending on musical tastes and expectations. Heavyweight components, slightly odd ergonomics, really odd appearance, non-fatiguing sound. Probably worth the money, but SO much competition these days. These just don't "do it" for me as I have (I'm spoiled) noticeably better.