Help finding a subwoofer

No suggestions but two comments.

First an 8" woofer plus passive radiator is still just an 8" woofer. A passive radiator may look like a woofer but it's just a port substitute.

Second, I know there are arguments against this but I'd look for a sub with a high pass crossover that rolls off the bottom of the main speaker. This takes a big load off the main speaker allowing it to play louder and cleaner.

Just installed an SVS micro 3000 in my living room system and I am simply blown away. Something so tiny can perform this well?? I was a bit taken aback. I have an SVS PB 2000 in my man cave and this little micro is right on par. To me the 2000 is laid back presence, the 3000 micro is speed… both produce extension, both are easy to adjust with the app. Both simply disappear. Size wise the 2000 is very big and would have never been sanctioned by my better half in the living room. The micro is so small it can be a bit more hidden. I’ve really only had a couple days with the micro, but I am just thrilled with it. I bought mine through the outlet tab on the SVS site and save a few clams. I recommend it highly. 
 

P.S. nice reviews from well known HIFI mags.

I have 2 listening systems, both 2 channel audio. SVS SB 3000 in smaller system, main system SVS SB 4000. Both offer, via my I phone a bluetooth system for adjusting level outputs. It is wonderful to sit in your preferred listening area and make adjustments sitting down. No more up and down, back and forth. Good luck, Robert TN

I've said it before in this forum and I'll say it again, REL subs seem to be the one type of audio gear that almost everyone can agree on as being well built, having excellent performance, and a good value. In fact, I don't think I've seen a negative comment yet about an REL sub, although one person didn't care for the customer service.

What’s your budget?  Incidentally, I don’t know if you can use onboard DSP if you use high-level inputs.