Update from Reddit:
Unidentified part in the top right is TI OPA1642A.
Unidentified part directly above the DAC is TI OPA1662.
Thanks to u/SightUnseen1337!
Today I decided to take a look inside my FiiO E10 Olympus 2 Headphone Amplifier and USB DAC. Overall, this is a pretty good-sounding and well-made budget USB DAC/Headphone amp combo, with a few small gripes.
Datasheets:
http://china.makepolo.com/mpp_21/268g...
http://www.alldatasheet.com/datasheet...
http://www.ti.com/lit/ds/symlink/lm26...
http://www.ti.com/lit/ds/symlink/pcm5...
http://www.ti.com/lit/ds/symlink/lmh6...