Mine is currently in review so I myself am waiting for the results and its with people that have the Penguin, etc (like I did). I paid enough on that and with all the upgrades I had to make to cable, battery (buying charger) and still it needs updating it costs more than the ones I got.
Note the one I get is based on a design from a guy who sells through USA so I won't take credit I supply some parts and do some soldering and eventually will probably supply all parts locally and improve the board design but some parts just cheaper from states, japan or else where than UK.
Note the one they (reviewers) have is better than the standard spec I posted the details for in another thread and as before has 12v of rechargeable power and so will drive the fullsize headphones quite well. I have tested it on my RS1 and HD650's. As for loudness where the Penguin goes say three quarters to a given volume this will get the same level in about 1/4 - 1/2.
If the reviews are poor I won't do any more that simple but from what I've heard (of course I'm biased hence the independent reviews) it beats comfortable any portable I've heard and compared to the big amps its on a par with a lot of well know names.
I've been selling off my headphone amps. My Graham Slee mark IV sold on eBay last week. I'm now chasing a none payer for my Project Headbox but I only want to remain with one main one and one portable one.
So hopefully will get some feedback this week. Hey guys if your reading this thread get the reviews in