Well I tried the ATH-M50 profile and it doesn't sound half-bad. The DT770 and ATH-PRO700 MK2 sound pretty awful though.
With it on, there seems to be added treble energy, almost sibilant to me, the bass is reduced in quantity so it's more balanced, and the midrange is brought forward. Switching to the normal/no profile, it's very evident to me that the midrange is laid-back and the lower-midrange gets veiled somewhat from the bass.
iPhone 4S (320 kbps MP3's) -> FiiO L3 -> C5 (bass boost off) -> M-100's
If you download the free app, I think the M50 works the best from what I've tried so far. If you have any other profile suggestions, feel free to give me a holler since I have the paid app and unlimited sound profiles.
Thanks mice. I am extremely happy with the Audioforge Equalizer app (really brings the "dull" Touch 5G sound to life imho), but I will try the Accudio with the M50 profile and see how it sounds.