Just put a prewired OBP-1 into my Fender MM5. Love it! Got it from BEST BASS GEAR Aguilar OBP-1 - Aguilar Preamps - Aguilar - Brands - 4 knob, 1 Switch, Quantity of Controls 4 knob, 1 Switch . They prewire Aguilar OBP-1, OBP-2 and OBP-3 preamps in any knob/switch configuration you want. Also Bartolini preamps and others. Their service is a real treat for every bass player that doesn't want to spend ours reading wiring diagrams to get the preamp into the bass. They also prewire all kind of other stuff. Great service, highly recommended!