First- I have nothing against hard rock, metal, death metal, fast playing or your Guitar Gods.

Many metal players posting here seem to have tone issues and want help, but they've chosen some of the shittiest gear I can imagine. What did you expect from some digital distortion pedal, solid state amp and a guitar that looks like it was made only to poke someone's eye out.

You're playing metal. You can't do so on a cheapass rig, or it will sound like it. Despite what the kid at Guitar Center told you, that Line 6 amp isn't going to sound like a Diezel Herbert, Dual Rectifier or anything even close. Stop complaining about shitty tone if you keep making obviously poor gear decisions. Stop buying with only your eyes, and buy with your hands and ears instead. You'll get much much farther. I'm not saying that you need to remortgage your house, but be smart about it eh?

EDIT: Yes, there is a huge amount of tone coming from the player themselves. If your rig is emulation, software, solid state or whatever and works fine for you... then great! You aren't the problem here, but rather people with shitty rigs that can't figure out what is wrong.