The Morley AB box is good - its true bypass and passive meaning the only thing the 9v power is for is to run the LEDs. And its quiet. It also doesn't care what direction you run it in, meaning you can run it as an "either or" control for 2 basses running into one amp, or you can run it as "either, or, or BOTH" from 1 bass to 2 amps (or 2 channels on one amp). See:
Morley Pedals - ABY Switching/Routing
You going to run one channel clean and one channel with effects?