There used to be an open letter to CBI owners on the Theta website (www.thetadigital.com). You might try emailing them. As I recollect, the CBII has some cosmetic changes (blue vacuum display), some slightly more substantive mods (the CBII is programmable via RS232 using free software; I believe any input can now be mapped to any output; output names freely definable), and some additional real mods (jitter jail now built-in, as well as DTS and DD5.1, more filter options). This is from memory. I could be wrong on some points. Didn't impress enough to shell out the bucks on the upgrade.