Best Big Sub? or duals?

Check out HT Shack subwoofer Tests. Look for low group delay, high SPL output (without compression) and low distortion. (If you want audiophile music quality then THD less than 1% is a worthy goal but near impossible to find in most commercial subs)

I am not concerned with music as much with HT. I am running vandersteen 5a with two 12" built in subs in the main speakers. They are increable and rock the room for music. I need more something for effects and i do listen to some dts music dvd's so it can't be all movies. But I want to feel explosions in movies.

I would look at REL. I have a Stentor and couldn't be happier.

REL is very good. I have just what you need for HT. A pair of Nelson Reed 1204s. They were designed by a California company for the movie industry to play back soundtracks at full volume in large spaces. They will reproduce 20 Hz at 120db levels. They use 4 12" Volt drivers on each channel, 2 forward facing and two facing back. The cabinets are large but not huge. I have the electronic crossover for them. When I used them on the cannons in the 1812 it would scare you. They were only used for a year or two before I moved into a smaller house and packed them up , where they have been the last 14 years. They were reviewed in Stereophile in the late 80s. I will sell them for$2900 with crossover, which is a fraction of the cost of building something like this now. The freight will be considerable , as they weigh 110lb each. I had intended to keep them but my present listening room will not hold them and I do not contemplate moving. There is info on them on line.

JL Audio Fathom F113 or 112