Well, I think BH has another hit on their hands with the Crack OTL amp. I finished mine on Saturday morning and have been "hooked" ever since! I'm having a hard time wrapping my mind around how such a simple circuit can sound so good. Bass is thunderous and tight....mids warm and present....and treble crisper and more detailed than any transformer coupled design I've heard, even my enhanced S.E.X. amp. The amp just sounds "right" - very balanced without having any solid-state coldness or glare. In fact, I'd go as far to say that this OTL amp has all the bass and speed of good solid-state with the warm mids and non-fatiguing highs of tubes. In short, the best of both worlds - and only $199!
Compared to my enhanced S.E.X., the stock Crack is very close. The S.E.X. amp maybe sounds a touch warmer, with highs that aren't quite as eye-blinkingly clear. Bass is similar, though the Crack seems to go lower and definitely sounds tighter. I'm surprised that the two amps would even be comparable, actually, as I remember there being a much bigger sonic gap between my headphone-kluged Quickie and S.E.X. amp. The Crack gets about as loud at full power as the S.E.X. amp through a pair of 250 ohm Beyerdynamic DT880's. Even 32 ohm Grado SR-60's work very well on the Crack, though I'm not a fan of how they sound on good gear (the bumped-up mids and treble work great for wimpy SS-amps in iPhones and the like, but are overkill, IMO, on tubes). It's nice to have a headphone amp that stands well on its own - I can now do a lot more serious listening in my library/computer room instead of always having to juggle discs in the living room to use the S.E.X. amp. And, I don't feel like I'm missing out on anything. I would imagine the upgrades will only make this amp better. I have the 6080's less modest cousin, a new-production Russian 6AS7 (a great "showoff" tube, IMO) on its way as well.
Kudos to BH for getting such a great product out there so quickly! I'd be interested in hearing other people's first reaction to Crack......
PS- Here's a photo of the bone-stock amp. I've only polished up the bell and stained the base a red mahogony color. My intention is to blue the bell and create a very high-gloss poly finish on the base, before attaching the famous BH badge. I'm a fan of minimalist, clean looks, and the textured aluminum plate seemed to go well with this scheme sans paint.