The inputs use 20 bit convertors. Yes, omni outs are 18 but this won't be a reason the desk would sound noisy.
My main point is that it won't be the convertors that are causing all this noise (unless the machine is faulty!), but more likely incorrect gain staging or the preamps being used with high gain.
> For some reason there was a brief stint where everyone and their mother had one of those for live sound and I hated it.