Some people like it simple and only listen with one source. In case of systems with my transformer coupled D3a phono stages this can simplify things considerably. Said phono stage is well capable to drive the inductive load of an AVC. Hence a passive volume controller is all that is needed if the system gain is sufficient.
Just a single knob for volume control.
One set of inputs and two parallel wired outputs (just in case).
I usually prefer a proper active line stage which decouples the sources from any difficult load and in turn provides low output impedance to drive long cables to power amps. But in controlled environments like those this unit is intended for, a passive one will do.