Headphones

If you need an extension Headroom.com has best selection. The DiMarzio silver at @$60 for 10ft extension
is very nice, I own one. Really you should look into getting
Clou Blue Jaspis to replace stock Senn cord, it is 3 meters
and looks and sounds great for $90. I recently bought one for my Senn HD580 and Garfish also just purchased one for his Senn HD600.

I have another thread started on Blue Jaspis where I will have to post more detailed info.

I did not read all the responses but have extensive headphone experience and own many of the highend brands and flavor of the month headphones.
I have own the HD600 and HD650s. I would pass on them. They lack dynamics and need specialty amps to sounds good.
I would buy as an alternative the Mass Drop version of the Focal, the Focal Elex. This headphone is $650ish and has a similar tone to the HD650s but has better everything. I do mean everything. I have also owned the HD800S and sold them after direct AB with the focal Elex. The HD800S has great (and I mean great) sound stage for a headphone but are bright with poor bass impact/depth (very poor IMO).
Grados are colored but worth having. I would pass on RS1 and buy the PS500e. It has a much cleaner midrange and softer more balanced highs. I have owned about 5 different pair of Grados and kept only the PS500e around, grados best headphone imo.
I have owned so many headphones and really you could just get the Focal Elex and be done. It is 95% there regardless of cost to anything on the market. They don’t have the deepest of sub bass but good enough (much deep/stronger than the HD600) and the sound stage is smaller than the HD800S but much bigger than Grado or Audeze for example.
For amps, you could start and stop with a Cord Mojo, really that good as long as you use easy to drive headphones such as the focal or grado.

Just FYI, this post is 20 years old. 

Hello, I strongly recommend the Naenka wireless Bluetooth headset I am using now. It is very light and uses Qualcomm 3040 chip. It can be used for 7 hours on a single charge and the total battery life of the charging compartment exceeds 28 hours. Music needs for business trips.