jonathan s.options.numOutputBusChannels = 10;
When doing, this the scaling and shifting should be handled in the background. I say "should" because I am not sure I tested it, but that is the expected behaviour.
Perhaps confusingly, when increasing the num BusChannels, you will still be able to access the corrsponding analog channels with the AnalogIn and AnalogOut ugens. Make sure you do NOT use AnalogOut on those channels you are using as audio.