I have a Hartke 5000 bass amp with a Hartke 115XL Cab and i was playing it at practice today and it sounded like it might be blown. I messed with all the setting i had on the amp head and i still got the same terrible sound no matter what i changed. i have the head hooked up to the cab on the Low Freq 8 ohms and the bi amp is on mono. I dont know what else i can do. help please.