Well, I'm sure the Miracles sound pretty miraculous out of a Hifiman but I can only talk about my experience with more "modest" IEMs : )
I Have a Hifiman HM-801 which I tried with some Westone 3. I did not like the W3s. There was too much emphasis on the bass and the highs with quite a bit missing in between. Some people have described them as "fun" and colored, the W3s did not amuse/entertain me much = sold!
Then I upgraded my Hifiman with a balanced card mainly for my Sen HD650 which turned out to be a wonderful combo even though I ran them with a regular non balanced cable straight into the balanced jack-in of the Hifiman. This combo is simply jaw dropping.
Back to IEM, I got a pair of Triple-Fi 10 that sounded a whole lot better than the W3s... Super transparent and spacious, gorgeous highs, tight bass, smooth mids, yet, a tad lean/recessed. It felt like it was missing just a tad of guts in the lower mids/mids. I just wished they had just a tad more mids to make them sound a little more "full", "rich".
So, I gave a try to the Westone UM3x and have to say, I am VERY happy with the sound. They are not as transparent as the Triple-Fi but still very detailed with the touch of warmth I was looking for. Compromise compromise but I'm happy with them and let go of the Triple-Fi...
One note on the balanced card as I read some comments from people who could not hear any difference from the stock amplifier.
For me, I was a little skeptical at first and must admit the card takes a lonnnnnnnnnnnnnnnnnnng time to burn in (300-400 hrs!!!)
I thought I had to have a special balanced cable to really take full advantage of the sound. I recently switched back to the stock amp just to see if I could tell any difference and WOW! it sounded very muddy/loose/dark in comparison to the balanced card. There is no way I could go back to the stock amp after experiencing the Balanced card. Maybe, whoever couldn't tell any difference between the two amps didn't take the time to burn in the balanced card, or never heard of cotton swabs!..
Anyway, hope it helps, cheers!