Maybe it depends what subgenre of metal

I have the 58x and personally like them for metal cause of the good quality mids and not too forward treble, as well as a decent amount of bass. Don't have many other headphones to compare them to though, but I definitely prefer them to my ATH-M40x, although I don't dislike those.

Not sure wtf OP did to that cable. I remember braiding a cable to make it shorter on a pair of AKG headphones once, cause the cable was non replaceable and 3 meters long, but I'm pretty sure that's not what this is.

Common Hifiman build quality L

Personally I'm with you. I'd be willing to spend maybe $400 max on headphones, whereas my studio monitors + sub were about $800 total. Sound quality (especially the treble and low bass) is better on the speakers, but sometimes I want the sound to be more intimate, in which case I prefer to use my headphones. Also gaming is better with headphones most of the time.

There could be slight unit variation, but it's more likely you're just imagining the difference. If there is a difference it's so small you wouldn't even notice it.

I've heard mixed things about the 660s2, a lot of people seem to prefer the 600's or 650's. Haven't heard any of them myself though.

Had mine for 4 years now and they're still going strong. Haven't even had to replace the pads yet even though I use them for hours daily.

"And with light came disparity."

Why does this look like it could be from a Souls game?

Not gonna lie, I don't generally find IEMs to be particularly comfortable, at least with heavy use. Doesn't matter what size tips I use, unless I want them falling out, my ears are going to be sore if I wear them all day. I prefer to use lightweight over-ears any time I can. I can wear my HD 58x all day and barely need to adjust them. My ATH-M40x on the other hand can feel a bit heavy after a while so I don't wear them much anymore. If I want something really flat I'll use my speakers.

Even started using my 58x at work/outdoors powered by my phone, and the drop in sound quality is hardly noticeable to me. Maybe 5% worse bass perhaps but that could very well be placebo.

Bought my last pair of headphones (HD 58X) like 4 years ago. They sound really good and don't require anything better to drive them than my cheap audio interface.

Because of the really good value you get from buying Sennheisers on Drop, I feel like I'd need to spend a ton of money to get a big upgrade in audio quality. Maybe if I have a money to burn one day I'll get a really expensive ($1000+) pair of headphones and a proper dac/amp to drive them, but I'm honestly content with my current setup. If it ain't broke don't fix it.