If you're looking at the ATH M50, I would recommend a cheaper headphone called the AKG K240. I'm pretty sure open headphones are supposed to sound better than closed headphones. Although I've never tried the ATH M50. The AKG K240 was recommended to me as an alternative to the M50. I'm pretty new to headphones, and I've only owned this pair of AKGs and the Sony V6, and a pair of HiFiMan HE-400, and Sennheiser Amperiors, and this pair oif AKGs is much better than the V6. I got these AKG K240 headphones and I have barely taken them off since I got them.
I'm a huge metalhead, I listen to extreme stuff and light (generally speaking) metal, and other music. I'd say if you're looking for a starter headphone to get the AKG K240 and Go Dap GD-03 amplifier for 20 bucks on amazon.
The AKG K240 is open so it doesn't block out noise, in case that was a concern for you.
If you're gonna recommend AKG k240s, don't forget about the superluxes. I might be starting to sound like a fanboy here lol but they are amazing quality for the price. They sound similar to the 240s. People commented that the original hd 681s were similar to the k240s except for the harsh highs. Well now they have other versions like the 681 evo and the 668b. Those might be considered more neutral and even better for metal.
I have the 681 evos, they probably suit metal and rock better than the m50 because of the better highs and slightly more controlled bass