assuming all the connections in your system is tight...can you check and see if the subs are blown?
you can do certain things to narrow down the problem. since you say the amp is getting power, but the subs arent playing, im thinking the sub is blown, or the amp isnt getting a signal.
if you have an extra pair of subs you can test one of those theories...since ive never messed with those High Input thingys...i cant comment much on those.
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