As a prototype of a larger project, I've just placed an order for parts and boards for a headphone amp design I'm working on. I've been "blogging" about it on my G+ profile (https://plus.google.com/106845099405832446739/) There are several pictures of the process, different layers and the schematic there too, but here's the board itself.
It's two amps in one: An op-amp based solid state DC coupled amp (lower left corner), and a simple class A tube/FET hybrid amp (most of the middle), with a switch that selects which one you use. My personal opinion is, which style of amp sounds best depends on what music you're listening to. In general, something mastered on tubes probably sounds better on a tube amp. Something mastered on solid state probably sounds better on solid state. And I _HATE_ swapping cables around between amps and inputs (hence my larger project; more on that one later.)
I'm looking for a few folks who know their stuff who might be interested in buying one (at cost) to build and provide feedback on. The kit, components and board, is about $150, depending on what tube you choose of course, without a case. That's cost, no mark-up. I'm not looking to get into a business here, I just want to make an awesome amp.
Parts show up tomorrow and the next day, boards will probably be early next week. After I get one assembled and have a chance to give it a listen, I'll be sure and post an update.
If you've got comments or questions, please let me know. :-)