Wellll. Thing is, you can get reeeeeeeaaaaaallllyyyyy close. Same as with VA synths. Problem lies somewhere else. It's still a piece of code inside a computer. There's no physical elemnt to it. Even if you build it in a box, it wouldn't feel right for the true metalheads. ...needless to say it would be kinda nonsense as you'd have to equip the box with "clean" amplifier to reproduce those digitally distorted sounds, which might be technically actually tougher than just to build it the old way.