Only a few: bias voltage selection, input selection ( bal/unbal) and power on/off.
The first two are implemented based on bistable relays - connecting them requires only momentary power consumption - important when powered by batteries.
Last is simple monotstabile switch.
Because of the relays, the housing is large, but maybe someday I will find smaller relays or think about another solution.
(Instead of a discrete stage, I would see a high-voltage OA here :))