Liked your stuff Supertoaster! I'm actually thinking of getting a Deathadder, up until now I used mouses more suitable for claw-grip, but I've noticed I use palm-grip more oftenly than claw. I also thought of getting the Beyerdynamic headphones....Ended up buying my current ones =P
Mouse - SteelSeries SenseiGood for claw and palm grips, a bit slippery, but it has cool stuff to tweak with. To be honest I prefer the XAI over this one, just that sadly my XAI's rubber under the left button got worn out after about 2 years (causing every single click to be a double click).
Keyboard - Ducky Shine MX Red, blue LEDsSimple, but awesome. Very well made, feels like I can smash it against the wall and it will be fine. Very comfortable to type (very fast too due to MX red). Has some nice simple features.
Headphones - Denon D2000The only "proper" headphone I got to use so I can't really compare. Obviously it's pretty amazing compared to cheaper headphones and any headset I've tried. They're quite heavy because of the metal, but really comfortable.
They're half-open headphones so the isolation isn't a strength of this headphone, but it's fine for me.
Since I bought them I've been listening only to FLAC, WAV and mp3 320kbps. You can even hear if the songs weren't recorded with high-quality equipment sometimes, which can be a disadvantage sometimes (rare).