And at the end of year 2012, I come across HiFiMAN once again, with the help of good friends!
CON: Slight channel mismatch in the upper frequency range.
ON SECOND THOUGHT #2: Other than regular stock sleeves, RE-272 also comes with biflange ear sleeves, which boost the response above 10 kHz. Combine these biflanges with shallow insertion, and the frequency response will become even closer to the diffuse-field reference.
ON SECOND THOUGHT #3: There is a removable acoustic damper within the nozzle, effectively controlling peaks in the mid to high frequency region. Unless peaks are desired, removal of the damper is not recommended. Moreover, the vent is merely a depressurizer- blocking it is not recommended either.
The electroacoustic performance of RE-272 is simply outstanding, eventually changing my preconception on HiFiMAN brand. Chinese manufacturers really have improved over the years, and I can now confidently recommend HiFiMAN and Vsonic products to anyone! (No, I still won't recommend Heir Audio.)