Ultimate Ears SuperFi 4

I bought this headphone, Ultimate Ears SuperFi 4, in February 2011, for $29.99 from Logitech.com. I guess they were liquidating some of those unpopular models from their inventory. Fair enough.

PRO: Light-weighted. Matte metallic finish is pretty darn sick too. Drivers of each channels are excellently matched!

CON: The frequency response is not well balanced & its bandwidth is just too short, even for a balanced-armature IEM. According to Logitech, the treblt of SuperFi 4 goes up to 15 kHz: that is just not true. Moreover, the 3rd-harmonic distortion figure goes over 1% at the mid frequency range, and this amount of odd-harmonics is very likely to be detected even by normal listeners with sensitive hearing .

ON SECOND THOUGHT: Just like TripleFi 10, SuperFi 4 is just too bulky to be inserted all the way to the ideal insertion depth. And for some reason, the polarity of SuperFi's drivers are inverted! Please don't tell me this is a manufacturing error...