Nice looking headphone amp. I've been looking for a portable one of late. I use the headphone jack on my Scott 222C tube amp for headphone use, and let me tell you it really blows me away! I use a lower end pair of Grados, the SR-60. I only wish they worked as well outside, but since they are essentially small open speakers, I hear mostly the noise of the rest of the world when I use them on the subway or the streets of NYC. Not what I need when I'm listening to music to block out the constant honking and such. I just ordered Etymotic ER-4P headphones for travelling. I've got a little cMoy homemade amp that I'll try using with them at first.
I buy my tubes from here: http://tubedepot.com/
They have, on average, the best prices, cheapest shipping, and are always reliable.