It's an overdriven Marshall JCM 800, all tubes amp, an old SS Peavey bass amp, run clean, and an old all tubes Ampeg SVT, overdriven with an Xotic BB Bass Preamp run into it, all run simultaneously, of course with each their own cabinet.
Or at least it was in that gear rundown I watched where Lou shows and explains about his live setup:
Lou Barlow is another one of my absolute favorite bass players.