There is an another post on Portable Source Gear subforum (http://www.head-fi.org/t/644688/the-accudio-app-by-golden-ears-a-headphone-revolution), but I feel we need to talk about this for more engineering/scientific sides here.
RIght now I can't test this app extensively, since I am out of the town and having only K551, T1, LCD-2 and Beyer DT 990, but my impression isn't that great.
What bothers me most is that because there are differences in each drivers, there is really no way to make clean flat frequency with just using some sampled measurements. I am sure you guys visited Tyll's site once, and realize even Audeze's LCD series, which is quite consistent in terms of driver quality these days, has some good variance in frequency response.
Otherwise, at least it is refreshing to see people trying to use those measurements into something actually useful. Android version is in works (for a year, lol).... it would be great since most of Androids support OTG for external portable dacs.
Edited by wnmnkh - 4/18/13 at 10:50pm