SVS Ultra with Samson S1000. Goes deep, is quick and accurate. Everyone who has heard this sub in my house has left in awe of the impact this speaker dishes out. You have to experience it to believe. My room is only 12'x18' but one of the sides is completely open to the rest of the house which is 50' long. Check out all the experiences of owners at www.hometheaterforum.com. You will be hard press to find a better sub for ht anywhere especially for the money.
