Just FWI - Rule out the Sennheisers ( well at least rule out the 555, 595 , 598 ) , the Beyerdynamics and the HM5( ficher audio clone) are far stronger headphones.
I would also suggest you consider the Sony MDR-1R ( I just got the bluetooth variant for about $280 usd and I love its sound )
Also do add a pair of grado's to your collection eventually, you'd be mad not to experience the Grado sound, But for a 4-8 hour-a-day headphone, pass on the Grados until you're more invested in Headphones as a hobby :P
** Just to comment on what has been said above, in reference to your choice of Metal as your dominant genre , I do believe the HM5's pack a considerable punch, the Grado's perform very well with metal ala Megadeth , Slipknot, Cradle of Filth.
Open Sennheisers have notably weak bass, even when EQ'ed , a Bassy Senn would be the HD220-pro .
The Sonys I have mentioned have a fantastic signature, and perform great for my favorite rock , Pearl Jam , Megadeth , Manson.
Open Beyers are weak on Bass, but perform very well when bass is properly EQ'ed for them, its just not in their flat-eq character. However I've demoed the closed DT-770 250 ohm , and i love how it presents bass.
Just my 2c
Edited by Necrontyr - 1/14/13 at 2:01am