Hi all,
We are aware of this routing issue on some versions of Mavericks and Yosemite. Looks like an OS X bug since it affects other products with different USB platforms.
There is a possible workaround which we found to work in most cases: in the Audio Midi configuration window, go to Multichannel Mode, and ensure that it is set to a valid Multichannel mode, for example 5.1, NOT stereo. Stereo audio should then return to the correct channels.
Hope this helps.