bobby:~$ speaker-test -c6 -Dplug:surround51 -twav

speaker-test 1.0.13

Playback device is plug:surround51
Stream parameters are 48000Hz, S16_LE, 6 channels
WAV file(s)
Rate set to 48000Hz (requested 48000Hz)
Buffer size range from 8 to 10920
Period size range from 4 to 5460
Using max buffer size 10920
Periods = 4
was set period_size = 0
was set buffer_size = 10920
Unable to set sw params for playback: Invalid argument
Setting of swparams failed: Invalid argument