I would have to guess that the answer to your question is before and after. New ones are probably the reconfigured version, older ones (could be sitting in a warehouse at Coffey, B&H, etc.) are the old one.
Thanks Phil! The PSC box labeled July 05. So I'm thinking it's before the Expo. Otherwise, I get quite good sound from the Promix3. There was this one time I compared the AT4073 with the Oktava in another thread. The Oktava was monitored through the Promix out into another recorder. There wasn't too much coloration, but I can't say anything else about the other mixers because I haven't tried them. Anything that you guys suggest and speak out, I'm always willing to listen.