[MrSandMan]

Metallica should be pretty easy to nail. I don't have my roadster anymore.. but I'm guessing:

turn down the treble to 11ish o'clock
Mids 12:30 - 1ish
Bass (depends on cab) probably 10:30

Precence to taste- (prolly 2 o clock)
gain would be 3 o clock.

This is just a wild guess. I could be way off.

For Pantera, your not going to nail his tone with a stock Roadster, Dimebag used lots 0 stuff in there. Like (2 -I think) Furman PQ3s. I tried a old 1980s greenface PQ3 with the Roadster and it didn't do it for me. The Furman sounds amazing with the Randall RG100ES.

I'm not sure if I can help you out with getting Dimebags tone from the Roadster. You'll need a pedal or parametric eq.