Holy smokes that bass punch is increased!
The treble and midrange are smoother, bass notes are better defined, and cymbals are a little more audible at home (no modding). The soundstage has also opened up a bit, giving the M-100's more width. The sound isn't substantially different from my E7, which was about 1/4 the price of the O2/ODAC and is much more portable. So if you are in the market for a USB DAC/amp with the M-100, I think the FiiO products should be just fine. The O2/ODAC seems more refined and smoother, but the difference isn't worth the cost in my honest opinion. I originally bought the O2 to power an AKG K 701 in the future, which does need more "oomph" than what the E7 can give.
Unfortunately I might have to exchange this O2 unit since the headphone port is very finicky. I made an unboxing video for YouTube but I'm hesitant to upload it because my audio test went horribly awry due to that port. :/
OK what gives? It only happens to the M-100. It works perfectly fine with my SRH940, HD238, Sennheiser CX-300, and MEE M9-BK.
Is it because the M-100's cables have the 4-ring plug (L/R/ground/microphone?) instead of the standard 3-ring one (L/R/ground)?
With the M-100 the audio produced from the O2 had a very prominent reverberation effect sometimes. Upon plugging in my headphones all the way, and loading a media player, the L/R stereo channels sound like a single mono channel. Pulling the headphone jack out a little fixes the problem, but wiggling the headphone jack even the slightest bit either causes the left or right channel to go out, or I get a very tinny-sound with no bass response.
I can do all of the above (wiggle the jack, pull it out slightly, put it in all the way) and get perfect audio out of the aforementioned headphones.
EDIT 1: Yes it's the 4-ring connector. Reversing the cable fixes the issue. Darn 4-ring connector...
EDIT 2: I don't think anyone has mentioned this yet, but the SharePlay cable seems much more pliable and flexible than the standard SpeakEasy and Boom Pro Mic cables. Odd. I would use the SharePlay cable more because of this, but it's 6 ft long, which is cumbersome when walking around school and on the bus.
In order of stiffness Boom Pro Mic > SpeakEasy >> SharePlay
Also, the SharePlay cable's colours are darker than that of the SpeakEasy (at least for the white silver scheme)
Photo showing the colour and bendability differences between SharePlay (left) and SpeakEasy (right) cables (Click to show)
Edited by miceblue - 10/27/12 at 4:05pm