Trying to figure out audio mixer input section/preamp

[Yamin]

Hi guys,
I'm going through this schematic of a soundcraft EFX8 mixer. I was hoping that you could breakdown the function of the transistors and how the gain is controlled via 10Kohm pot. This is a common circuit I see with other mixers too. Also could you direct me to some resources which explain these kind of preamp circuitry.

Thanks in advance.

[magic]

It's a differential pair of open loop common emitter amplifiers.

Each PNP/NPN combo is a Sziklai pair, acting like an "ideal" PNP (high β and very constant Vbe).
The bases are biased to ground by resistors and modulated with input signals.
The emitters simply follow the bases and differential input signal appears across the gain pot.
AC current equaling differential input voltage divided by pot resistance flows through the pot and C500.
The pullups to +V2 provide emitter bias, but gain pot current subtracts from one of them and adds to another.
The two different currents pass through the Sziklai pairs to their 1.2K collector loads wired to -V1.
Differential voltage appears at the resistors.
Gain is 1.2K over gain pot resistance, maybe ±6dB. Do the math, I'm lazy.