The "aucat socket" was removed ~7 years ago. I've dropped the .Xr to audio(4) as the output could be anything on the network.
OK? Index: cdio.1 =================================================================== RCS file: /cvs/src/usr.bin/cdio/cdio.1,v retrieving revision 1.62 diff -u -p -u -p -r1.62 cdio.1 --- cdio.1 19 Mar 2017 18:40:11 -0000 1.62 +++ cdio.1 2 Oct 2019 06:05:45 -0000 @@ -99,11 +99,7 @@ Unlike .Ic play , the CD player need not be connected to an audio device; instead it rips tracks from disk and outputs audio data to -the default -.Xr audio 4 -device or -.Xr aucat 1 -socket. +the default audio device. Both individual tracks and track ranges may be specified. If range is specified in descending order tracks will be played in descending order. If the first value in the range is omitted, tracks from first track on disk to the specified one will be played.