ATRguitar91
SS.org Regular
I currently own the 770, 880, and HD600. They're all great in their own way. If you're going to using them for guitar and want to stay in budget, I'd go with the DT880s. Incredibly comfortable for long sessions and pretty neutral. I keep mine at work and wear them for hours every day. Open is definitely the way to go if you can. Once you hear open headphones it's hard to go back to closed.Regarding the headphones, considering comfort and an enjoyable (rather than 100% accurate) listening are a priority, is there any set closer to 100 EUR that will do the job? Or should I just stop being a cheap stingy miser, and get the good ones?
In terms of the budget, I think there is a pretty severe drop off once you get below this bracket. That said, there's no reason to buy brand new headphones. I got both of my 770/880 used for around $120 US. If you're going to be playing primarily through headphones, it's a more than worthwhile investment.
The only open headphones under $100 I've found that I like are the Panasonic SHP9500. They''re very comfy despite not having very deep pads, and they punch way above their price range in sound. The treble is a bit grainy, and the bass a bit anemic, but this can be fixed to a point with EQ. If you just needed them for general listening I'd recommend them and do to friends. Since you'll be using them for guitar and possibly mixing in the future, I'd go for the 880.