If you have something like the Roland VS-1680, Akai DPS-12 any of those multitrack hard disk recorders do you still need a mixer or do they serve as a mixer also?
i once owned the vs880 by roland and on that machine i only had master outputs (left, right) on the rear of the machine which did not do much for me as far as mixing into an external board. now i`m not sure if you have an output for every track on either machine which i believe you don`t so i would suggest that you mix form the machines itself.