I've had the Miracles for a while now, and find them to be one of the more challenging headphones to amp and this is owing entirely to the treble. I never did agree with the reviews describing them as treble-tilted, or sparkly. In fact, I found the treble distant, placed further back in the stage, and lacking shimmer. The ride of a cymbal was short, and somewhat detached from the rest of the spectrum. I didn't like them out of a Pico Slim, SR71A, SR71B. They improved with the Stepdance and a little more so out of the MK3, but the treble was still hard to discern and seperate from the immediacy of the bass. If you ever heard the HE6 and found the vocals on a forward plane, almost pushed forward by several feet from the rest of the ensemble, this is similar to the miracles treble, which was pushed back instead. Surprisingly the iBasso DX100, with its smaller soundstage (compared to the MK3) handles the Miracles beautifully. With my other customs I prefer using an external amp, but the Miracles are the exception. The treble has come forward and has pleasant clang and shimmer. The details are consequently pushed forward too. I still find them to be on the warmer side of things, but a definite improvement from before.
The bass is still the best I've heard, neck and neck with the Audezes, and they remain unchallenged in the jazz and classical department (for iem's). Tonally, they are on par with my other customs, but this field is where I feel iem's have no business competing with full-size, open headphones.