hey, my current set up is a laney rbh800 head, hughes and kettner br 410 h cab, and fender precision bass. basically whenever i play, every now and then I get a really crackly sound coming from my cab, and the sound starts to fade out until it totally cuts out. then a few minutes later, the sound gradually gets louder and louder, until its back up to full volume again (best i can describe it). This is soooo irritating cos i just got em! So does anyone have any ideas what it could be? all items are second hand, and im sure its not the bass itself, so it must be the amp right? Thanks!!