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 150 Ω 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 150 Ω set of headphones looks like 600 Ω at the input, a suitable load for most good quality line output stages).