The default format of Plan 9 audio streams as expected by /dev/audio is a 16-bit LE integer, stereo, sampled at 44.1 kHz
Plan 9 /dev/audio is preset to take s161e, stereo, 44.1kHz because The default PCM format s161e predates plan 9. s161e is the only reasonable choice for a default PCM format, being the most widely used encoding method across various industries.