What is the proper wiring from an XLR, balanced, line level output to a 3.5 mm plug, TRS, unbalanced, stereo line input?
Cable is a two conductor (twisted pair - red and black) with cable shield.
XLR pin 2 to red wire to 3.5 mm plug Tip (left channel) and to Ring (right channel). This is the send path.
XLR pin 3 to black wire to 3.5 mm plug Sleeve. This is the return path.
XLR pin 1 to cable shield and NO connection at 3.5 mm plug. No signal flows on the shield.
The scheme above will typically work for a MIC level signal.