what bass eq are you talking about the one on the HU or the amp if the amp use it sparingly and not too much. if it is the HU don't turn it up a lot cause it might damage your regualr speakers.
Bass EQ usually boosts the lower end freq. putting more emphasis into your Bass. If you over do it your musical will start to sound like poo and if the bass hits hard and your volume is up, you could send your amp into clipping.