I strongly recommend the Sennheiser HD 25-1 II (it is on-ear, but sound-wise for metal it is very, very good). AKG K371 is another option to look at, but for metal the Sennheiser is hard to beat.
So I bought the AKG k371, after taking a trip to a bigger town where I had the oppurtunity to test the k371 and the DT770 against a "power metal" sample list:
SAMPLE LIST LINK(youtube). I quickly noticed the DT770 are definitly not for this type of music, but they had a nice spacious sound if you disregarded the lack in other fields.
So my conclusion after some time spent at home with the headphones is that the AKG k371 are an "okay", "decent" headphone with a good price but a main major flaw for me are part of the vocals(as explained below).
AKG 371 opinions:
Cons(sound):
The biggest letdown of these headphones are that the vocalists that have a brighter voice get muffled, darker, more distant, not as clear and high. Which means that the signature goosebump notes dissapear in the "power screams?". This is very noticable in this song: "Twilight Force - Enchanted Dragon Of Wisdom".
Song Link(youtube)
Another very noticable example of this "distant/muffled" effect is in the 12 second intro to:
"Skeletoon - Brighter than 1000 suns"
Intro Song Link(youtube)
The whole song "NorthTale - Shape your reality"
Song Link(youtube) is ruined with these headphones unless you EQ, because of the type of vocalist.
The second con for me is that they lack a bit of body and punch in the drum department, noticable in all songs, still miles better then DT770.
Third main con is that they don't sound very spacious.
Pros(sound):
Good sounding vocals, with the exception of goosebump notes.
All different kind instruments sound good and separated.
Good balance and representation between vocals and instruments.
Atleast they had some degree of punch in the drums even if it could be more.
Song most suitable for theese headphones from the sample list:
Beast in Black - No Surrender.
Song Link(youtube)
Also overall seem to suit powerwolf tracks, avantasia and other darker voiced vocalists.
Build Quality & Comfort:
Somewhat uncomfortable headband, but you get used to it.
Drivers a bit to close to ears.
A bit loose headcup sliders.
Mediocre quality overall, but acceptable for the price.
Conclusion:
If I had no outside parameters I would always reach for the X2s instead of the k371, but im not unhappy with the k371, they are ok for their price and purpose and become a good headphone with some EQ adjustments in the 4k-8k range.
With the above in mind what should I go for in the open cans I should buy?
Are the Sundaras still a good option?
Unfourtunately due to corona the retailer didn't want to open new boxes so I could test other headphones.
Im considering prdering the 2020 HE400i blind just to see if I like the sound signature that is comparable to the sundaras?