The SB-900 is an inexpensive and relatively compact subwoofer from the folks at Atlantic. It's also one of their most popular models, but it's not optimal for everyone's setup. To meet the needs of more home theater enthusiasts, Atlantic has created a down-firing version of the subwoofer which allows for far more options in placement.
Like its front-firing cousin, the SB-900DF offers an 8" woofer powered by a 125 watt amplifier. It goes down to a frequency of 32Hz and up to 200Hz at a peak output of 102dB SPL. It sports distortion-detection circuitry that helps avoid unpleasant sound and takes advantage of "floor coupling" which improves the sub's bass response. Like the SB-900, the SB-900DF is available now at a price of $349.