Yup, for natural stereo recordings, I prefer ORTF or mid-side recordings. But for what chris wants, it's a different matter
My goal is to one day own a soundfield ST350 (or whatever replaces it) for location recording.
The 6sn7s are for the single ended outputs. The 6sn7s are fed ground instead of input if you're using hte headphones. The single ended outputs are always active.
There's a contradiction there.
because the default usb audio driver is for usb 1.1, and was written to handle 48/16. Other people have custom drivers or custom chipsets that can handle more, and run at usb2 speeds.
large and medium format cameras are definitely not for birding. APS-C is the format that will suit birding best, imho.
LF and MF cameras are best used in studio settings, or for other shots where long exposure times are acceptable.