Hey there, I'm currently running an Ampeg V4BH with a Sansamp RBI to add a little bit of grit (I'm planning on selling the sansamp and moving to a pedal OD, but would like to use it for now). I have the Sansamp hooked up from the output to the power amp input on my ampeg, and it sounds great. I recently picked up a powered gator pedal board and 3 pedals.. I got from left to right a Korg Pitchblack, Diamond Memory Lane Jr, and an Aguilar TLC compressor. I'm not sure what the ideal way for hooking this up would be so that I can still use both my Sansamp and Ampeg's Pre. Thanks a lot! Looking forward to trying this stuff out together tomorrow!
To toggle between the Ampeg preamp and the external preamp, you need: --a Y cable to split your bass to the inputs of the two preamps; --two short cables, one from the output of the external preamp, and the other from the loop send of the Ampeg; --an A/B footswitch, to select from each of those outputs. The switch's output goes to the amp's fx loop return. In some cases the Y splitter can cause problems like tone loss or even feedback. If that happens, get an isolated (active buffered or transformer iso) splitter box to replace the Y.