I'm not Gonk, but I play one on tv. That note in the manual is for the sake of the amplifier, not the 990. I logged a request with Outlaw support about this prior to buying the 990 and they confirmed. The 990 will send a signal from both the balanced and unbalanced outputs at the same time without a problem. However, having two inputs going into the same channel of an amplifier could be bad, thus the note.