New-to-me head doesn't like active electronics

For years I have been trying to reassemble my rig from 25ish years ago. I recently acquired the Peavey Firebass 700 I've been looking for from Facebook marketplace. The guy swore it worked, but after driving 3 hours to pick it up, it did not. He felt bad and just wanted it gone (along with the Peavey 410 to complete my rig), so he knocked about 60% off the price. After getting it home, I tested the cab with my old Peavey Mark IV, and it sounded great. I tested the Firebass head through my Hartke 210 with my Sterling Musicman and it crackled and popped. My guitar player's friend cleaned the pots and tested it out with his Squire P bass through the 210 and it seemed to work perfectly. I tested it through the newly acquired Peavey 410 and my old Peavey 412 with my Warwick Corvette and my Sterling Musicman (both with active electronics and new batteries), and it sounded terrible. Very little volume, crackling, and bad tone. I tested it again through the full rig with my guitar player's Squire P bass (passive), and it sounded great. Thunderous and clear volume and tone. I tried changing various settings while playing with the active basses, including the passive/active button, but nothing helped. The only difference I can determine between all the testing is that the passive bass sounds great on it, and active ones don't. My main bass is the Warwick Corvette, so I really want to be able to play it through this rig. Hoping to find answers here before I spend money getting it looked at by a professional.