Recently, I purchased Infrasonic Windy6, which is made in South Korea. My decision might look random, yet the purchase was done extremely selective to suit my measurement-recording needs.
According to reviews done by ixbt & guru3d, its (I-O looping back) performance is great- possibly better than other higher priced interfaces from well-known manufacturers, such as E-MU or M-Audio. (And my own measurement agrees with ixbt & guru3d) I've had E-MU 1616 for some period of time- however I was not really impressed with it; the software was unintuitive, hardware DSP presets were useless, and the headphone output had a lot of hiss noise & high output impedance. In contrast, Windy6's software is quite straight-forward, and its headphone output has output impedance less than 5 ohm, which is a great feat for driving multi-driver IEMs. (= no need to add an extra headphone amplifier just to drive them.)
Once I am done with constructing a new ear simulator in a few months, I will be finally able to post some measurements of my own.
Update on 3/21/2011: Windy6 is in South Korea right now. Salsal will analyze it with AP, which is a professional audio analyzer. Hopefully I can get some positive feedback from him. :)
Quick measurement links
Headphone measurement data by brands:
AKG • Apple • Astrotec • Audeze • Aurisonics • Beyerdynamic • BOSE • Brainwavz • Brookstone • Creative
Earsonics • Etymotic Research • Fostex • Final Audio Design • Grado • Heir Audio • Hidition • HiFiMAN • JAYS • JVC
LEAR • LG • Martin Logan • MEElectronics • Maxell • Monoprice • NuForce • NVX • Ocharaku • Phonak • Radius
RHA • Rockit Sounds • Samsung • Sennheiser • Shure • SONY • STAX • Suyama • TDK • T-PEOS • Ultimate Ears
Wall of Shame (coming soon)