That amp will not be the best fitting amp...but here you go. I think it is safe to assume that its a 4 OHM SVC sub.
Specs for amp.
4 x 25W @ 4 ohms (0.08% THD - 20Hz-20kHz)
4 x 35W @ 2 ohms (0.8% THD - 1kHz)
2 x 70W @ 4 ohms bridged (0.8% THD - 1kHz)
There is not much you can do except bridge 2 of the channels. Use the + from CH1 and the - from CH2 and run them to the sub. It probably will tell you how to bridge the two channels on the amp itself.
