Assembling the XLR steel case
Unpack the parts. You should have 2 big steel parts, 4 standoffs, 2 distance rings and some screws.
Start assembling the Raspberry Pi on the bottom part.
Fix the standoffs with nuts on the DAC+ XLR and plug it onto the Raspberry Pi. Put the the distance rings to XLR connectors.
Now add the top over. Start fixing it with the screw on the top.
Finally, fix the XLR connectors with the black screws.