I have a 400 Watt amp and speaker setup I used for mobile discos. I am only using a 15 watt practice amp on my bass at home. Is there a sort of pre-amp I could use on the power amp so I could use it to jam with my mates. I understand it wont sound as good compared to a proper bass amp but is there anything I could get just to mess about on? The speakers are a pair of 1X15 and a horn.