Little Red Cue Box

[mtodd]

Hi All,
I need some help. I have a D1600MKII and use an old receiver to power it to monitor speakers. The receiver has "A" and "B" speaker switches. A friend (that I can't reach) suggested I purchase a "Little Red Cue Box" headphone distribution box and hook it up to the "B" speaker outs so multiple musicians could plug their headphones in. He even made a "3 pin Female XLR connector cable with one end having the three wires free and tinned. He said to hook it up to the "b" speakers? There's my question. I'm sorry I must be dense but I'm not sure how to hook it up. On the back of the receiver there are the speaker outs posts. Red and Black for right, Red and Black for Left. The cable he prepared for me has three wires. How do I hook it up?