Need help with Bose and my new head unit!!!

Hey guys whats up. When i bought my Z28 it had the bose sound sytem in it and a crappy jensen head unit. I got a new JCV head unit for X-mas and just got in installed. They guy mentioned somthing about a Bose amp in the car but i wasn't realy listening. Now the head unit seems to be powered by the amp so much that even then the volume is on level 1 the music is loud and it starts to get unbearable only at 1/3 volume. I'm pretty sure the head unit isnt designed to be like that. Is thier a sepreate amp with the Bose? Is there a way to adjust it or turn it on and off? Thanks - Mike

he has obviously never installed a stereo with a bose in it before. You need to step down the signals from the stereo before the speakers.

how do I do that? is it somthing i can do myself or should i take it back to them? I would rather try and do it myself if i can. -Thanks