I've never played a 4Pro and that cabinet, but I did look online at the front panel.
Geez.
That's a Whole Lotta Tone Control, what with the knobs, the graphic, the push switches, I can see where you could stir up a mud puddle with this real fast.
IF it were me, I'd make sure the graphic was on bypass, all those 4 push in tone switches, out/off, and the rotary tone knobs as close to whatever neutral is on that thing. If you're running an active bass through it, set your bass flat and check how the input pad changes the tone in or out if it has one.
Then listen.
If it's still too much deep end, start cutting frequencies with the graphic only until it sounds more like you want and work out from there. The idea of subtractive EQ is almost a foreign idea these days, but sometimes the right amp, the wrong cabinet in the wrong room, you start boosting things and it just runs away real fast into something utterly unuseable.
I'd also put something between the cabinet and the floor to eliminate any chance of floor coupling, which just adds deep end.
An old trick we used to use to kill the boom in small rooms/stages was to face the cabinet backwards. I don't know why this seemed to work sometimes (and I'm sure @agedhorse is laughing at me, or shaking his head!), but some places it was a big help.
Then he's going to post he's playing and EB bass with tapewounds . . . . . .