A-B Selector with volume cut on B

[primedynasty]

I need to build an A-B box to run my two basses into my amp.  One is a passive signal coil bass and the other is an active humbucker so the gain differences between the two is huge.  I want to be able to switch between the two and have a adjustable cut on the b path so I can keep the active bass at the same level as my passive bass.  Is there anything out there that does this.  I know Tonepad has a nice A-B Selector, but how do you cut the volume?  I am pretty new to this and have only built one pedal so far but it was a blast.  Any help is appreciated.

[DWBH]

You can use a potentiometer, wired up as a voltage divider.
Also, you can use a small cap (200-500pF) across the lugs of the pot to preserve some high end.