If active with a passive option, a SEPARATE passive tone knob.
The best implementation of this I’ve seen is the MTD Kingston Saratoga Deluxe preamp. Only the 3 band EQ works in active mode and when you switch to passive the EQ is bypassed and only the tone knob works. So at the flick of a switch you can instantly go from bright HiFi modern tones to subby tone-down thump.
This system works better IMO than what a lot of other brands do, which is have the treble knob become the tone knob when switched to passive, meaning you have to keep changing the position of that knob if you want a really bright active sound vs a really dark passive sound, or vice versa.