That would change the voltage drop across the resistor and depending on the circuit, the output voltage/current. In many pcs of equipment there is also an RC filter network that is part of the output. Some have an emitter follower circuit, and others use this resistor as part of a negative feedback network, changing the resistor opens up a whole can of worms. Designing it with low output impedance in the first place is a much better idea. If by just changing the resistor Sherwood(the manufacturer of the 990) could have lowered the o/p impedance, don't you think they would have done this to keep it low, we both agree lower is better? It is not as simplistic as you make it out to be. You just can't change one component and have no worries about other effects.

Tim