This product allows the connection of a stereo balanced line input via 2 x female XLRs and creates a headphone output, with level control. It is transformer balanced, and can be used with any headphones above 150Ω impedance. The transformer ratio of 2:1 ensures that any headphone load presented at the output is reflected through to the input at a 1:4 ratio (hence a 150Ω set of headphones looks like 600Ω at the input, a suitable load for most good quality line output stages).
The stereo headphone output uses a stereo 6.35mm jack socket with the following connections:

Pin Type & Connection:
Tip: Left.
Ring: Right.
Screen: Ground.
The headphone level will be at half the level of the incoming signal with the volume control at 100%.
The volume level control sets the output level of the stereo headphone socket and runs logarithmically from zero to the maximum output level.
The stereo analogue input is on two female 3 pin XLR connectors with the following pin assignments:
Pin 1: 0V Common.
Pin 2: Phase.
Pin 3: Non Phase.