John,
Here is a response from Dominik Hartl at TI from a similar issue.
"The output signal from the AIC3106 looks ok. The codec architecture is delta-sigma, which pushes (and shapes) quantization noise out of the audio band. What you see here is the high-frequency noise, which is expected and inherent to the design.
If you hook this up to a speaker, the noise won't be audible due to its high frequency (it will all be shifted above the audio band, e.g. above 20kHz, if you sample at 44.1kHz).
You can verify this by running the signal through a spectrum analyzer and looking at the result in the frequency domain."
More information on this issue can be found on the TI e2e forum[1].
[1]
http://e2e.ti.com/support...ers/f/64/t/2489.aspx