No, Edwin. Stan uses the pickup selector switch on each bass to switch between them by placing one in standby.
All three inputs on this preamp can be used simultaneously and there is no level change.
Part of the product development on this is changing the chassis to a custom made one for the purpose. Like I mentioned previously, this enclosure is an off the shelf one we used to simply get it done. At one point, I thought we were going to have to put some of the jacks on the side of the enclosure just to get everything to fit.
As it was, we did have to modify some parts slightly to cram it all in. Dad had to file a couple thousandths off the sides of the pots. A couple of the jacks needed some minor modification too. The enclosure has a lot of dead space at the corners and the handles to protect the switches take up some real estate too, so we had to cram things tighter than we would on a product, but that's what custom is all about!