They're not considered the best of the best but they're good enough. Deep bass doesn't need to be perfect. The room causes far more problems than the driver. I've got a 14 year old DD18 that works fine and I'd never consider replacing it unless it stopped working and I couldn't get it fixed. It's a great product. The deepest bass without a hint of audible distortion. Sealed box means no port noise. There's auto eq and manual eq. It's a thoroughly thought out product with several generations before it. The question is just whether you want to risk buying an excellent older product that might have a part fail. Can you get a replacement?
velodyne dd plus? still considered best of the best?
are these subs still comparable to the top subs today for music and sound quality? I was thinking about getting a used one, the resale value puts them around the same price for me as a new svs sealed 3000 series, new ryhmik , new rel t7i, or used jl audio e series