Disclaimer: This IEM was sent all the way from Singapore. Much appreciated, Nate! Measurement h as been carried out at the reference plane with a pair of small Westone mushroom tips. Unfortunately, it turned out his pair is faulty on the left.. :-/ Thus, only the electroacoustic performance of the right unit will be discussed in this analysis.
I first auditioned this IEM at the CanJam 09, which was held in Los Angeles, California, along with Westone 3. As far as I can recall, my initial impression was just "OK" and UM3X was slightly more linear than Westone 3, at least to my ears.
And four years later, one of the regular visitors of my blog, Nate, sent in his pair for analysis with specific requests. And as always, I never turn down a friend's request ;)
CON: Not only the polarity of the IEM is inverted, there's a funky pre-ringing present in the time domain (a cosine burst?). Although it should be inaudible due to the effect of temporal masking, such electroacoustic behavior has never been measured previously.