Thanks for the update, Ray. I received my SR71b last night, and I immediately plugged it into my newly-acquired (used) Lavry DA-10, feeding it SPDIF from my computer. I used the XLR outs with a TWag XLR to SR71b adapter and plugged my SR71b-recabled Edition 8s in. I guess I'm going all-in when it comes to adopting the 71b plug--the Protector made me a believer in the technology, plus the plug's small size makes it ideal for portable use, while an XLR adapter can easily be used for stationary listening with a balanced desktop amp.
I plan to do a more thorough listening session, but so far I'm very pleased. The sound seems slightly more forward and aggressive than the Protector, which I recently sold but I remember being a bit more laid-back. Like with the Protector, there is absolutely zero hiss when I plug my JH16s in, and the black background really allows details to be heard easily.
One thing that's bothering me is that the volume pot seems very stiff and difficult to turn. I guess it will gradually loosen with time, and a stiff pot is better than one that's too loose, but right now it's hard to do very slight adjustments in volume. My Protector had a much smoother pot, and was never so loose that it was hard to control.
Right now, I'm listening to the SR71b with my HM-801 and JH16. I initially forgot to set the input to SE, and was wondering why the sound seemed a bit distant and tinny. Clicking over to SE accentuated how forward the vocal presentation is (at least relative to the Protector). The soundstage is still massive, and makes for a very euphonic experience with songs that have widely dispersed placements of sounds. Headphoneaddict's observation that custom IEMs can be listened to comfortably in high gain is accurate, although the volume is too jumpy at that setting for me, so I've been listening in low gain for better volume control.
Overall, it seems like the SR71b is an amazing achievement for its size (not much bigger than the Protector in terms of total mass) and price. I'm hoping it will be my all-in-one solution for full-size cans and IEMs. Has anyone tried the SR71b with HD800 or LCD-2 in fully balanced mode yet?