Well, here is the dirty little truth about headphone amps (and let me come right out and say it's only my opinion and take it as one anonymous guy's subjective opinion and nothing more); headphone amps don't do much and mostly sound boring. I suspect most of the problem is with headphones themselves and not the amps. Since the transducers are right up against the head and ears, the sound is constrained. No room acoustics. We headphone enthusiasts have some compelling and misdirected notion that if a headphone amp has a huge case and is filled with lots of goodies it will provide us with what we have been heretofore lacking, that with lot of power or some other voodoo/hocus-pocus (huge tubes jutting out like Woo or Zana Deux or any number of others, wires going everywhere and nowhere as in the Single Power fiasco), the gates of audio nirvana will open and our cans will now have all the unconstrained dynamics and sonic glory that were previously constrained and hidden (sorry for the flowery prose). That is the real nature of the beast. All that said, I do still think that a well designed, powerful amp with low output impedence can make many headphones sound their best. And now back to the BHA-1. We shall see.
Thanks, Fsonicsmith, for this comment. It has been my experience, limited though it is, that while headphone amps make a difference, confirms yours that that difference pales by comparison with the difference made by headphones themselves. Perhaps this is why so many headphone enthusiasts buy multiple pairs. With the exception of the high end Stax, it seems you may get a bigger bang out of your buck buying additional cans than buying a high end amp.
But your comment also reinforces the basic point about headphones - by their very nature they are not like listening to speakers. The experience can be very good, indeed, but it is a different one. It makes sense to demand that good headphones (together with good headphone amps) be accurate etc., etc., but it is not reasonable, I believe, to compare the headphone experience directly with that of one's main system.
For me, the chief attraction of the headphone experience is to take it in its own terms. Fsconicsmith, you say, rightly, headphones inevitably have a constrained sound. Depending on the gear you use, that constrained sound can feel very intimate, warm, and most pleasing, which may be why so many headphone enthusiasts like tube amps, and headphones that add to or enhance that kind of sound. For example, many admire the accuracy of HD800s, but it seems only a minority love them.
As to the BHA-1, in terms of the tastes I personally have developed in headphone use, if this new amp is very accurate in all ways, but detracts from rather than enhances the intimacy of the headphone experience I have come to prefer, then I probably will give it a pass. I had a headphone amp that did this (a Grace Designs m902 which is seldom mentioned in the headphone community) that was pricer than the BHA-1, and no doubt was most excellent, but wasn't for me. I gave it to a person doing pro work, which made it perfect for his use, but not mine. I hope, therefore, that the BHA-1 targets the headphone community rather than the pro market.
Dave