mazdaspeed sub problems

[Hakkola]

My buddy has a mazdaspeed protege and his sub has stopped working twice now.

So today he got new MTX subs installed appearantly with one MTX amp and one kenwood AMP.

The sub doesn't work already, any idea what the problem might be?

[deadsilent2]

it can be a number of things. does the amp turn on when he powers up the deck? if the amp does turn on, then the problem lies in the subs