You have a male 6-pin mini XLR (or TA6M) connector on your tinybox. The pin configuration is probably like this:
pin 1: low-voltage mic power supply (for FET)
pin 2: right noninverting input
pin 3: left noninverting input
pin 4: high-voltage mic power supply (for polarization voltage)
pin 5: right inverting input (may not be used for AKG)
pin 6: left inverting input (may not be used for AKG)
You need to measure the voltages on pins 1 and 4, and you need to measure the resistance to ground (= chassis) on the signal pins. This information should be sufficient to build you a preamp.
This datasheet contains the pin numbers for male connectors):
https://www.mouser.com/datasheet/2/393/TA_MS_CD-773078.pdf