Flexibility is not something one usually associates with wired headphones. After all, you’re tethered to your equipment. You can’t go out, hop up and get a cup of coffee, and you can’t do a lot of adjustment to the sound profile as well. Wireless headphones promise to do a lot more. Aside from the flexibility of being able to get up and move around, that will without a cable tied to your head. But also the idea is you could adjust the sound to your own personal specifications, as it were, because wireless headphones have digital signal processing on board. So if you need to, you could tweak the sound. The trouble is, in cutting the cable. Obviously a lot of the sound quality got cut as well. Sennheiser now has tried to solve that problem with the HD630s.