#1
So I plug it through my Peavy Vyper 30...

I can't seem to get a good metal sound and the buzzing is pissing the *** out of me...

Can I blame the guitar?
#2
I bet the metal tone could be due to the Peavy and the settings on it. The buzzing, I have no idea, it could be the cable, cause that yamaha has hum-bucker pickups, but don't take me seriuosly…
So I don't know what you can afford but if you're playing more pro-like I'd buy not a Yamaha but a Gibson, ESP, Dean, that kind…
and the amp Marshall for Metallica/AC/DC or maybe a Mesa.
I haven't tried a Peavy, but from people that I know, they don't use it on metal.

So don't blame the guitar or the amp, just recheck settings and gear.
#5
So it's not the problem with the amp, right? Because I bought it less than 30 days ago. If that were the case, I would need to go back to get a metal amp. -_-