Bass goes deep, but also has an excellent airy punch --reminiscent of the FXT. Mids are liquid smooth, slightly warm, rich, & effortless.. vocals sound incredible, tonality & timbre is simply superb --reminiscent of the RE262. Treble is balanced, very detailed, & smooth like a monitor, but possess that perfect touch of sparkle (the sparkle reminds of how it sounds from my reshelled DBAs). All this wrapped in an articulate, cozy, studio monitor-inspired warmth --reminiscent of the GR07.
The soundstage is wide and deep.. but not so wide it sounds artificial. This goes hand in hand with the imaging.. which really stood out to me: pinpoint precision like I've never heard in an IEM. I like the stage's positioning too: probably about 5-7 rows back (perfect for a studio monitor, IMO).
Right now, they're a little warmer through the mids than expected.. which subsequently get a little congested with some overly complex, bottom/bass heavy pieces.. but I'll report back on that once they burn in some (and get properly amped).
I'll echo what another user mentioned about the technical prowess of these phones.. I keep coming back to the word effortless.. the UM miracles just seem raring to unleash & show off their muscle.. but always remain "studio monitor" polite and controlled.
These impressions were heard unamped from the iPhone 4 (I haven't manged to unglue myself from the couch to grab the Arrow). One thing is for sure, the Miracles definitely like to be amped.. I've got the iPhone's volume at around 90% where it's plenty loud but they sound like they would surely take advantage of some extra (high quality) juice. I'll also cosign on the comments about how natural the decay sounds.. in a stereotypical sense, it's very "un-BA" like.. but has all the things we love about BA's (speed, accuracy, detail).
I'll continue to pepper the thread(s) with impressions along the way & will have a more in-depth review once I feel truly well acquainted with these.
Hats off to, UM.. I'm thoroughly impressed.