[UPDATED ON 10/07/12] Updated with the new simulator measurement, not mimicking the manufacturer's graph this time in order to retain the repeatability of measurement. It is very fortunate that my colleague provided me with a IEC-60711 plot of this IEM!
It's about time for some Ultimate Ears Triple.Fi 10 Pro already! The cable has been replaced with a furutech, which is of better quality than the black default cable.
I tried to match the manufacturer's frequency response graph (not from Logitech, but retrieved from the old Ultimate Ears website) with mine, and the result is as close as it can get.
CON: The frequency response of Triple.Fi 10 is FAR from the ITU diffuse-field target, which is a prerequisite for becoming a good studio monitor headphone. Also, its impedance characteristic varies greatly over the entire frequency spectrum- making the IEM hard to be driven effectively. IOW, you need a device with an output impedance less than 1Ω. The harmonic distortion figure remains below 1%, which is the audibility threshold for musical materials- yet still quite high compared to the other IEMs.
ON SECOND THOUGHT #1: Regrettably, Triple.Fi 10's physical bulkiness makes it virtually impossible to be inserted properly- With its default ear sleeves, you can never obtain the response the manufacturer intended when they first designed the product! I had to make my own custom ear sleeves by tinkering around cheap ebay-silicones in order to get a reference response in my ears.
Left: My data 3mm away from the reference plane with my friend's IEC 60711 data superimposed
Right: Manufacturer's official data
ON SECOND THOUGHT #2: It seems there are a lot of TF10's frequency responses published over the internet, but they do not quite agree with one another, even the manufacturer's product quality deviation in consideration. That is most likely due to different insertion depths when measured, and the current updated plot has been measured right at the reference plane.