i bought this amp used and sooo far... i'm not happy with the tone. it will get loud as hell but it sounds a little muddy. i'm playing a jackson kevin bond in drop tune B and not no pedal. i've noticed that if i really turn up the volume(5-6) the fuse will blow. do i need new tubes? what can i do to this amp to get a killer death metal tone? i was thinking about adding a 2 X 12 vader cab. any suggestions? thanx