I thought it would be interesting to have a look at what the data stream looked like between the Yeti and the PC.

So I fired up Wireshark and selected the USB port and well if you've never looked at wire shark before its a bit confronting

I know that audio out works so I set some music playing and selected the Yeti as an output. just watching the Wireshark screen it became fairly obvious what was what.

A stream of Data like in the above image would show up. The highlighted line is the PC sending a data string 1216 Bytes long to the Yeti. The Highlighted block towards the bottom of the image is the Audio string. With some music playing (Tiffany of Course) its hard to see what is what. So I set Audacity to output a 1 Khz tone firstly to both channels and then just to the left and then just to right. Having a consistent output made it easier to have a closer look at what was going on.

The Audio string with the tone to one channel looked like this

Now knowing what the signal is and knowing that it only goes to one channel, in this case the Left it can be easily seen that the signal is interleaved 2 bytes to the left then 2 bytes to the right (as there is no output to the right its value is 00).

Changing the signal to the Right Channel the order is reversed 00 first and sending the same signal to both channels the the first 2 bytes are the same as the next 2 bytes.

Now Ive identified what the data string looks like for a given input I set audacity to record from the Yeti and captured the USB data again. Which looks like this.

The incoming data is just toggling between FF FF and 00 00 at the sample rate for each channel. Next step is to find out a bit more about how the ADC works and determine what conditions would cause such an output - I Think I might be making some guesses as the Data sheet is garbage, there must be a different data sheet provided to purchasers of the CM6400 then is publicly available on their website.