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