I have a vox ad50-50 vt 212, and i love all my clean and overdriven tones with it,
but i can't get a distorted enough tone from it.

my question is, if i put a good distortion pedal in front of the amp, would i be able to get a decent metal tone?
You could with any amp. (I think. Never tried it with a Vox, but it works fine with my Fender on clean.)