Z-680 Center speaker has no bass

When a sound is coming from the center speakers it misses the appropriate bass. When I redirect the sound stream to any other speakers, the subwoofer reacts again. Might it be my audigy 1 or is it the cables. Or are my speakers really defect? It is quite annoying in games, there also seems to be way too much treble on the center speaker but that might just be my mind compensating for the bass loss.