Well that sticker, (I've noticed) it's appearing on all the new EBMM basses featuring the 18 volts preamp, i.e Bongo, Big Al, 25th Anniversary and it's succesor: the Reflex.
It is not really something you want to let your dinner get cold over the discussion of it. Even if your amp only has one input then what you must do is calibrate your input level so that the power of the preamp doesn't clip into "unwanted" distortion, then adjust your master volume accordingly. That's all. If your amp has this passive / active switch then use it as you see fit. There is this thing I've noticed with my Big Al and the 25th as both basses have that active / passive switch and that is that unless you pump the bass well above the middle detent mark, and you go from passive to active the jump in power is not that unfriendly or let's say overly high in volume. However if you are playing passive and you are just using your passive tone control while your preamp is set to mega numbers when you switch to active be careful as it'll knock out the fillings out your teeth. So before you do... adjust the volume by turning it down a couple of notches