What is the best subwoofer you have ever heard?

The two best subwoofers I have ever heard are the Revel B15 and the SVS SB13 Plus. I know there are better in subwoofer land but these are what I own and the best I have ever heard personally. Neither go the deepest(18Hz to 20Hz) but the mid bass punch and speed may be up there with the best.

I am using both of these in a 6000 cubic foot room and together the room does get pressurized.

Bill

That honor goes to the new Ken Kresiel DXD12012!

Custom built, 6' tall, 4' deep, 2.5' wide. Four 15" woofers in an isobaric arrangement. Double walled cabinet with the inner wall isolated from the outer wall, including panel deadoning components.

+/- 3db down to 18hz. Max SPL 120db.

If money is not an option I would purchase the bass engine from a pair of the Scaena loudspeakers, they are 3 stacked per side 18 inch woofers in a specially designed cabinet.

They go, low, low, low, fast and articulate with massive pressurization. Check out HP soundings review of the Scaeana's

There is no substitution for massive displacement of six 18 inch bass drivers and a few thousand watts of juice!

Well Matjet, I like subs that augment the main speakers and blend well. So for me it is the REL Britainia series. I have the B2. If you don't connect it off the main amp...then it will never blend and you will always be tweaking with it. I hate that, I never touch my REL its AWESOME.