The SMS-1 has an operating range of 15Hz-200Hz, but for a single channel only. Since low frequencies (and their associated problems) aren't limited to the just the subwoofer, MRC is applied to all channels.
Actually, the SMS-1 goes from either 5Hz or 15Hz (depending on the firmware version) to 120Hz - the display goes to 200Hz, but the EQ's can't operate above 120.