Cal Labs Gamma question

I ran across a Gamma DAC by California Audio Labs in my fatherinlaw's system yesterday while changing out his preamp. He used it for CD's with a Sony transport. What I would like to know is how good is it & what is it worth? He may want to sell it to do a cable upgrade. Help anyone? Thanks in advance.....
As I recall, the Gamma was Cal Audio's $99 entry-level DAC that was regarded as a good value for that price point. I have never heard it, but I have heard (and own) other CAL DAC's. I doubt you could get much for the Gamma. The Sigma and Alpha's are now at the sweet spot at their used prices (around $300 and $450, respectively). Keep in mind, too, that California Audio Labs is now out of business.

If you like the sound, I wouldn't mess with it.

Good luck,