Nice work Kingkorg ,
I like the dual mono stack approach .
Taking the output of a capsule as two seperate signals never really occured to me .
A cathode follower stage using wired in sub mini tubes might be an easy way to do it , typically you only need your grid resistor/cap ,capsule bias and one or two other components in the mic body itself , output circuit components and transformers can be located in the PSU , as its two single ended outputs not balanced , regular 7 pin tube mic cable should remain compatible and keep the abillity to vary polarisation from the psu if needed .
On digital processing ,
I did once experiment with the mic array on the Sony Ps3 eye camera ,
The Voxengo Pha-979 Phase align VST allowed me beamform the four microphone array ,
The webcam sampled 4 channels at 16khz so the results werent great for audio, I treated the linear four mic array as two stereo pairs(1,4 and 2,3) in terms of processing ,as proof of concept or as a lo-fi, low bandwidth ambient room mic its was a huge success , its like your position along with the shape of the room your in is changing before your ears . X-Y capsules and the polyhedral type array looks nice ,but four capsules eight preamps and your going to need multi core snake cable to connect it up , maybe an 8 channel A/D converter in the mic itself ,
a look at an ambisonic schematic might be an idea ,just to see how the pros do it .
