(2) SD-3 8 D4 - Sundown Audio 8" 300W RMS Dual 4-Ohm SD Subwoofers. Sundown Audio SD-3 8 D4 8" 300W RMS Dual 4-Ohm SD Series Subwoofer. We do not consider the SD-3 an “ultra-shallow” but they are as shallow as possible and feature several techniques to reduce the effective depth required.
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