Anything that will take an SE output (the Behringer mic - I think it's SE), and with phantom power. Luis may know better than I. He did make a custom pre-amp from high quality parts for his binaural head though.

http://www.musiciansfriend.com/pro-audio/rolls-mp13-mini-mic-preamp

EC2A3 comes to mind if Craig will let me steal one of them. The intent of such as design was to make use of the Levi. However, Schiit's upcoming Statement hybrid also comes to mind. Anax's S7 (tubes rolled for HD800) didn't work out too well and lacked sufficient gain (and probably power) to get moderate-high SPL. My main concern with tubes is sloppy bass. A Nelson Pass design would be interesting, but the NP integrated amps cost more than the entire system.

I am very happy with the Mjolnir right now. That circlotron circuit got's something special.

EC2A3 comes to mind if Craig will let me steal one of them. The intent of such as design was to make use of the Levi. However, Schiit's upcoming Statement hybrid also comes to mind. Anax's S7 (tubes rolled for HD800) didn't work out too well and lacked sufficient gain (and probably power) to get moderate-high SPL. My main concern with tubes is sloppy bass. A Nelson Pass design would be interesting, but the NP integrated amps cost more than the entire system.

I am very happy with the Mjolnir right now. That circlotron circuit got's something special.

Ahh of course, forgot about the Levi.

I was mostly thinking DIY keeping in line with the speakers. Pass becomes much more affordable

This looks like a fun DIY project.  How does the rear loaded baffle compare to the design of the Moth Cicada that you posted in the other thread?  Do you think the fostex drivers would work in a bass reflex cabinet design like the Cicada or would you be losing too much of the bass presence?

Also nice to hear that there isn't a discernible bass delay, seems like a common problem for the rear loaded baffle system.  I was worried it would take too much technical knowledge for me to try to compensate for that.

One more thing, how did you integrate the supertweeters into the system?  I didn't think you wanted to use any crossovers.

This looks like a fun DIY project.  How does the rear loaded baffle compare to the design of the Moth Cicada that you posted in the other thread?  Do you think the fostex drivers would work in a bass reflex cabinet design like the Cicada or would you be losing too much of the bass presence?

Also nice to hear that there isn't a discernible bass delay, seems like a common problem for the rear loaded baffle system.  I was worried it would take too much technical knowledge for me to try to compensate for that.

One more thing, how did you integrate the supertweeters into the system?  I didn't think you wanted to use any crossovers.

I do not like the bass from the Cicada. It very much sounds like the typical ported bass in a box - keeping in mind this speaker was from a prior era - right around the time when speaker companies started to put more effort toward making properly braced and re-enforced cabinets.

The BK-16 cab I like. The cabinet is very vibration free - doubled thickness baffle in front and back - the internal panels of the horn also providing mucho bracing. The length of the back horn seems short enough to not cause any notable delay in the bass. There's still some horn coloration, but it's much better than some of the larger back loaded horns I've heard.

The bass is very open with the BK-16. Not boxy at all. I still need to hear an open baffle bass speaker like Donald's.