I only have Anax's JDSLabs ODAC Rev B and my Massdrop O2 will probably won't be here till mid Sept.
I've read and worked a bit more with the 2i2 and I'm more convinced it will not be up to snuff to measure these devices unbalanced. I would have to come up with a way to seamlessly couple the unbalanced outputs of the O2 and ODAC to the balanced inputs of the 2i2. I will post some simple THD and IMD measurements to illustrate what I mean, along the results of other folks here and there.
The 2i2 is IMO a great pro-audio balanced interface, but perhaps a bit mediocre in unbalanced mode, like most entry-level pro-audio interfaces.
Nevertheless, I will put my measurements on the ODAC later tonite.