There is no way, IMO, a USB-powered anything is going to "slay" a good battery powered amp. Just play some complex orchestral music through the Dragonfly and listen to the soundstage collapse.

Specifics, please.  What recording, and "collapse" compared to what?

Btw, confirmed at the meet the Leckertons work w/ the iPad Mini via camera connection kit.

Ask Apple unless a camera kit for iPhones is already in the pre-production stage. For the 4S alone it would make a real difference given it's able to make good shots...

4G is good but its strengths are feature set and size.  Sonically it competes w/ a lower tier of amps like the C421, UHA4, E11, etc.  Next tier is the UHA6S and then moving up to the Triad L3, ALO RX3, Portaphile 627.

Just wanted to share my impressions of the portable Total BitHead amp. This is the first and only portable amp I own currently, and can only compare it against the Sansa Zip straight outputs. Therefore I'm not sure how this amp compares to others like the RX3, but I would definitively be curious about it.

No contest, Bithead is far overpriced for what it is, heck, it can't stand up to chinese amps.
It is "fuzzy" or "noisy" with anything that is sensitive and/or low or medium impedance (meaning most everything with minor exceptions, such as your DT990). Clearly not a generic amplifier for everything, unlike most of them. Feel free to measure it yourself.
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@Anaxilus: Kudos for the measurements. I see that you strapped the hardest IEM load ever to exist*  to the amps and tested with a dynamic driver IEM only once. Care to measure with a more normal load too? Also, what are you measuring into?

Seems that RMAA is doing something weird calculating noise levels too. E.g. Leckerton UHA-6 is about -110 dB(A) given the picture, but it says it's -90 dB(A). I wouldn't trust it for anything after that. Pity actual signal analyzers are expensive. However, a good software analyzer should work well. (Either dScope or TrueRTA, neither is free obviously.)

*Triple.fi 10, which dips to 6 Ohm at highest end, making anything with nonzero output impedance roll off. Also high capacitance, so many amps have degraded IMD at highest end. Also, there might be something even harder to drive around.