I own The Element.
It is WONDERFUL.
I use it on everything from my Senns to my Beyerdynamics to my HiFiMan 560s.
I listen to much Classical, Jazz, Livve, Acoustic, Rock.
It resolves everything very handily with a nice musicality and perfect neutrality that allows the music itself to shine.
Fast and with excellent clarity.
I have had no problem powering anything I throw at it and with the production that I am looking for.
It's also very elegant to look at and its footprint is right for most rig spaces.
I also own the O2...this one is better,(as it should be at the price point and the build quality), but certainly far less portable.
I see this as a prime rig dedicated desktop dac/amp, where the O2 is better used in smaller spaces or for your carry-to-other-places rig.
That being said, the O2 is nice as well. I have posted up a review of the O2 on its drop pages up in here.