My understanding is they revised the current DAC to get better performance and those are already in production. Units with the improved performance I don't think are in the U.S. distribution yet. I asked Trinnov support and they said to work with your dealer if you want to be certain you have the improved version. I was also told that serial numbers starting with below will have the tweaked DAC for better performance.
Altitude 16- 1308
Altitude 32- 1390
This information is incorrect. I recently purchased an Altitude 16 (S/N 1279). My dealer checked with Trinnov and was told that my unit has the DAC upgrade.