Some questions for a beginner

If I recall correctly the HD600 has less bass than the 598 - both of them didn't sound like heavy metal headphones to me - they're very laid back generally. The 'Sennheiser sound' is generally quite laid back, perfect for easy listening for hours on end, but not so good for super exciting fast music. This is subjective as others love the 'easy listening' aspect of these phones for metal etc, but I prefer 'energy' at the expense of increased listening fatigue, like the sound from Grado headphones (SR225i for example) 

I find a good middle-ground between the two is the AKG sound which generally has a lot of energy but can be heard for longer sessions. The K240 II and K701, K702 and Q701 spring to mind as good 'all-round' headphones. Although the HD600 also falls into this category. That said, most of these headphones would benefit greatly from amplification apart from the Grados and maybe the K240.

Can't comment on the price difference between the two Sennheisers.

What kind of sound do you like?

Do you like the soundstage to be big?

Do you like a ton of bass?

Do you like a forward vocal presentation?

Do you like bright highs?

Just so you know, a lot of metalheads gravitate toward Grados b/c of its guitar presentation.

Q701s for heavy metal, no. It doesn't really benefit from the perceived clarity and speed that comes with the leaner sound. Heavy metal needs some more authority and sweeter mids for those guitar shreds. For the rest of your genres, they'll work, but probably not that ideal. You'll need something more aggressive. D2000s have some really deep bass, are powered relatively easily, but not sure if the mids would suit your music. Grados would probably be a solid choice as well. They have those forward and nicely colored midrange, some don't like the treble presentation. 

Quote:

Originally Posted by TwinQY 

Q701s for heavy metal, no. It doesn't really benefit from the perceived clarity and speed that comes with the leaner sound. Heavy metal needs some more authority and sweeter mids for those guitar shreds. For the rest of your genres, they'll work, but probably not that ideal. You'll need something more aggressive. D2000s have some really deep bass, are powered relatively easily, but not sure if the mids would suit your music. Grados would probably be a solid choice as well. They have those forward and nicely colored midrange, some don't like the treble presentation. 

I would avoid the D2000 - the treble can be more harsh/shrill than some Grados.

Heavy metal meathead reporting in...

On a serious note...

While the Q701 is arguably the best headphone in your budget, it isn't really worth it without a good amplifier.

I also beg to differ on saying heavy metal needs a lot of bass, I actually think it's the mids which are far more important.

Anyway, if you really don't want to get an amp I'd say the 598 is your best bet, though I'm also wondering which source you're playing your music from?

Try considering the grados or pro 900 

I have tried the hd600 without an amp an it sounded horrible

the hd598 on the other hand does not need an amp but it lack bass 

Given your tastes i'd consider seriously Ultrasone. The HD598's do fine with soft rock and such kind of music, i've found that they lack the aggressiveness and speed that Ultrasone gives.