I've been eying off these little tube headphone amps for awhile, i think they would be a cool little useful gadget that you can build yourself that have decent audio quality. The one i've been most keen in purchasing is this kit from mr nixie, he has a great reputation with his nixie tube clock kits and also has this mini dual tube hybrid amp. He also offers some other interesting audio related gadgets like magic eye nixie tube VU meters and IN-9 bar graph nixie tube VU metershttp://nixiekits.eu/http://nixiekits.eu/MiniHeadphoneAmp.htm
I like it because it uses 6N28B type tube which are designed to use low plate voltages (less then 50V) while the others i've seen like the bravo or indeed units off eBay use a plate starved 12ut7 or similar tubes designs. Currently i have AKG Q701s which i recently purchased and i drive them off my Focusrite Saffire pro 24 audio interface which i purchased primarily to record guitar and keyboards but its the only device i have in house which has enough power to drive them. (mind you it a great sounding setup even if unconventional).
Has anyone purchased this particular kit and what do you think of it? The review i have found haven't been particular helpful.