Edirol MA-15DBK Digital Stereo Micro Monitor Bass Enhancer Up to 24-bit/192 kHz, DA conversion for S/PDIF optical &amp; coaxial input Subwoofer output port for bass boost 15 Watts per channel 3 independent source inputs; 1/8 Line, RCA pin Line (L/R), and S/PDIF (optical &amp; coaxial)