HSU VTF-3 MK5 HP

“You don't necessarily need an *identical* second subwoofer. But it should match your current PB-3000 in output capability. If you want something of similar capability, then the HSU VTF-3 MK5 HP is extremely close and "only" costs $1000: https://hsuresearch.com/collections/collections-true-subwoofers-subset-collection/products/vtf-3-mk5-hp-subwoofer Just be aware that it doesn't have any app support like the SVS subs do. For me personally, it's a non-factor when it comes to setting up multiple subs in a room. But some people really seem to like the app and consider not having it to be a dealbreaker. Ideally, you should be setting up multiple subwoofers through your AVR's room correction (DLBC, Audyssey XT32, or something similar) or via a MiniDSP. But if those are not options for you for some reason, I would recommend using this method to set up dual subs in a room: https://avrant.com/a-12-step-guide-to-setting-up-dual-subwoofers/”