So I pre-programmed a show with my SQ5 and 2 x DX168. At the venue I had to put the two stage boxes at the opposite side of what I expected, so I routed channel 1-16 to stage box 2 (ch 17-32) and channel 17-32 to Stage box 1 (ch 1-16). What then happened is that I got no sound on the first 4 channels on Stage box 2. re-routed 1 to 1 and every channel worked again. I am 100% sure I routed correct, and I also tried to route other channels to those preamps, with no luck. Any suggestions why this happened?