I have been thinking. My subs have nice bass. Only problem is they start to roll off at 40 Hz. My Crites will go to 35 but it sounds better with subs. I started looking aound. Flat to 20 ish. SVS, HSU, SPEEDWOOFER were all considered.
Used is hard to find. Local pickup.
SVS have prodigious output but the helper insisted you can’t mix sealed with ported.
HSU. More serious subs.
Speedwoofer. 10" will go to low 20s for $500. Description of parts sound pretty good.
All this and I’ve never moved my 1st two around. I just thought I could avoid all that by only moving the new one around.

