Abusing drum overheads and 2mixes! One thing I had to deal with in this particular case was the latency induced by the round trip through the Apogee AD-DA16X in order to run them in parallel with the input signal. A null test found the delay to be 82 samples or approximately 1.9ms. Fortunately the DM2000 has full delay and polarity reversal facilities which made this task simple.