I get "Expression failed" just by listing the outputs on my machine.
dcerouter_1:~# squeezeslave -L
Expression 'snd_pcm_hw_params_set_buffer_size_near( pcm, hwParams, &lowLatency )' failed in 'src/hostapi/alsa/pa_linux_alsa.c', line: 421
Expression 'snd_pcm_hw_params_set_buffer_size_near( pcm, hwParams, &lowLatency )' failed in 'src/hostapi/alsa/pa_linux_alsa.c', line: 421
Expression 'snd_pcm_hw_params_set_buffer_size_near( pcm, hwParams, &lowLatency )' failed in 'src/hostapi/alsa/pa_linux_alsa.c', line: 421
Expression 'snd_pcm_hw_params_set_buffer_size_near( pcm, hwParams, &lowLatency )' failed in 'src/hostapi/alsa/pa_linux_alsa.c', line: 421
Expression 'snd_pcm_hw_params_set_buffer_size_near( pcm, hwParams, &lowLatency )' failed in 'src/hostapi/alsa/pa_linux_alsa.c', line: 421
Output devices:
So, I'm not sure that is specific to the output device.