I'll back this up, nothing beats the HD800S for soundstage and imaging, particularly in the context of FPS gaming.

But the dual use for music makes it tough, especially since OP's genre preference is metal. The HD800S sounds far better than the average headphone for any kind of music, but it has pillowy bass, and shines with things like instrument separation and soundstage that pay off more with understated stuff, like classical music or acoustic. I wouldn't be shocked if at the end of the day you still preferred the XS for music. But for gaming, I don't think you'll find anything at any price point that's better than the HD800S.