Ah, I didn't know about the 29.4KHz rate. I don't believe it was mentioned in the old kernels and I've never read the full specs for the CS4231A. I'm guessing that makes a big difference. There's a lot of audible information between 11.05KHz and 14.7KHz.

If you're looking for a way to regenerate sine waves of a known frequency then I may be able to help. About a year ago I created a hijack patch to use the DSP's tone generators to produce any tone on demand. Unfortunately the patch never made it into the hijack tree, and since then some of the existing code that the patch relied on has been removed (I used the calculator UI for numerical entry), so it's not a completely trivial merge. The patch included ioctls and also included a fixed point library for the kernel which could be useful for doing other DSP related coding, athough I guess you've got such a library in the player codebase anyway.

Anyway, if you are interested then once I get the new alpha then I can create a patch against it.