Kicker S12L5 Problem

[Problemo]

Hey folks,

I was wondering if someone could help with a problem I'm experiencing. I have 1x SL12L5 sub connected to a kenwood mono block amp (KAC-151D) The amp itself running at 2ohms push's out 400 watts rms. I have wired the sub in parallel (at the back of the sub, + to + - to -) giving me 2ohms. I have 2 leads (+ and -) going to the amp but it sounds underpowered. At low volumes you can barely hear the amp no matter how much you adjust the gain or bass boost. This for such a loud sub doesnt seem right.

My confusion sets in when the amp has 2x sets of +-'s I know it has a set of terminals for both left and right subs but what happens if I only use one set of +-. I know its a single channel amp but the instructions are confusing, all configurations point to having two subs installed.

If anyone could help I'd be really greatful, the things begining to drive me up the wall now, I just wanna get the damn thing finished !

Thanks folks,

- Prob