AFAIK, no volume pedal can deliver a hotter signal than the instrument connected delivers. Which is to say, if the amp could survive without the volume pedal it should survive with.
Unless you have an active bass that is too hot for the passive channel, since you are trying to overdrive things, it seems likely you would want the hottest signal in, which would be the passive input.
Surely somebody will correct me if I'm wrong . . .
BTW I do the same thing with mu GUitar, using the volume control on the guitar. CLean at 6 or 7, dirty at full up.