Sennheiser HD 598. Thread closed.
Seriously though, the 598s (original beige and wood version) are under $150 on Amazon. How to best describe them, hmm. I would say in my layman's language that when you listen to music it sounds like the singer (especially female singers) decided to walk down from the stage and sing directly to you while standing just a foot away. It's almost seductive and sensual (haha, kidding, but you can get an idea of what I mean. Also referring to the female singers there.).
The instruments sound like they are separated and not bunched up. They sound natural. Together with the vocals, assuming you have good recordings, if you close your eyes or even if you don't you can feel like your listening to them in real-life.
About specific sound quality. I don't know, they sound great. I'm not a level 99 audiophile bard, so I can't really put into fancy words how it sounds. It just sounds really good, much better than any other headphones I had tried until these.
As a fellow PC gamer, I can definitely say that if you use these headphones, combined with the free version of the Razer Virtual 7.1 Surround software, you'll have as close to a high-quality home theater setup as you can fake on just two speakers. Especially on games with lots of ambient noise and loud effects, also in open-world games, you really do get a sense of being "surrounded" by sound (pun not initially intended but then begrudgingly allowed). That combo also works great with movies that have a multi-channel soundtrack (basically all movies that are not cheap rips). It's home theater on-the-(relatively)-cheap.
One thing to note: bassheads need not apply. You can get much heavier (although less natural-sounding) bass from $25 Sennheiser HD 202s than from this. But the bass in the headphones sounds right. You don't miss it much until you start comparing on tracks where the bass is meant to shine (which might not be many depending on what you listen to). I noticed it first on Taylor Swift's (don't judge) I Knew You Were Trouble's "bass drop". It sounds much more exciting on my 202s than on my 598s. From then on I've noticed it in various other tracks but it's not a big deal. In fact, the superior overall sound quality more than makes up for that little bit of "bass-liteness".
