ffplay -f alsa -ac 1 -i hw:2,0
ffplay version git-2013-12-18-aeccb52 Copyright (c) 2003-2013 the FFmpeg developers
  built on Feb  1 2014 10:25:57 with gcc 4.6 (Ubuntu/Linaro 4.6.3-1ubuntu5)
  configuration: --enable-gpl --enable-libass --enable-libfaac --enable-libfdk-aac --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libspeex --enable-librtmp --enable-libtheora --enable-libvorbis --enable-libvpx --enable-x11grab --enable-libx264 --enable-nonfree --enable-version3 --enable-shared
  libavutil      52. 58.101 / 52. 58.101
  libavcodec     55. 45.102 / 55. 45.102
  libavformat    55. 22.100 / 55. 22.100
  libavdevice    55.  5.102 / 55.  5.102
  libavfilter     4.  0.100 /  4.  0.100
  libswscale      2.  5.101 /  2.  5.101
  libswresample   0. 17.104 /  0. 17.104
  libpostproc    52.  3.100 / 52.  3.100
[alsa @ 0x7fd9840008c0] cannot set channel count to 2 (Invalid argument)
hw:2,0: Input/output error