The Headroom Blockhead can be purchased in a balanced configuration, but you will need specially wired Senn 650s to listen to it. check out head-fi-org.
Headphones powered by a preamp output?
Has anyone explored this idea? I'm thinking about ways to utilize the 2nd pair of XLR outputs on my preamp. Isn't it possible to wire the 2nd pair of outputs to a headphone amplifier or would you have better results driving a pair of headphones directly?