The rotary switch by the master volume chooses pickup - neck to one preamp and bridge to the other, reverses which pickup goes to which preamp, both neck, or both bridge. The toggle closest to neck is switchable hi/band/lo pass for one of the preamps (the other is just low pass, and small rotary between the volume and freq on each preamp is a variable Q), next switch puts the preamps in series for some interesting tone shaping, third takes the filter out of the second preamp, and the last one flips between stereo or mono (summed) out.
I've got a fretted bass also made at the same time, same small scale body, long scale neck, but very different body woods.
They both sound great. Recently using black nylon wrapped flatwounds on the fretted, and am going to try them on the fretless, which will increase the black factor (and also sound different).