Hey Rickey2, as someone who owns a pair of Apollo 16s and just ordered a Studiolive 32 Series III, I'm interested in this as well. Using the Studiolive 32, it looks like the only available physical outputs on the SL would be the 16 mix outputs (twelve XLRs + four 1/4"). So apparently only one set of inputs (or both 8-channel DB25 inputs) on an Apollo 16 could be connected using all of the aforementioned mix outputs. I'm sure you're already aware of this, just hoping to clarify for someone to understand your question (the original response indicates that they did not fully understand and think you're trying to use dual interfaces rather than the SL as your inputs/mic pre's feeding your Apollo 16 interface).