arecord -L

null
    Discard all samples (playback) or generate zero samples (capture)
default
sysdefault:CARD=Pro
    FastTrack Pro, USB Audio
    Default Audio Device
front:CARD=Pro,DEV=0
    FastTrack Pro, USB Audio
    Front speakers
surround21:CARD=Pro,DEV=0
    FastTrack Pro, USB Audio
    2.1 Surround output to Front and Subwoofer speakers
surround40:CARD=Pro,DEV=0
    FastTrack Pro, USB Audio
    4.0 Surround output to Front and Rear speakers
surround41:CARD=Pro,DEV=0
    FastTrack Pro, USB Audio
    4.1 Surround output to Front, Rear and Subwoofer speakers
surround50:CARD=Pro,DEV=0
    FastTrack Pro, USB Audio
    5.0 Surround output to Front, Center and Rear speakers
surround51:CARD=Pro,DEV=0
    FastTrack Pro, USB Audio
    5.1 Surround output to Front, Center, Rear and Subwoofer speakers
surround71:CARD=Pro,DEV=0
    FastTrack Pro, USB Audio
    7.1 Surround output to Front, Center, Side, Rear and Woofer speakers
iec958:CARD=Pro,DEV=0
    FastTrack Pro, USB Audio
    IEC958 (S/PDIF) Digital Audio Output
dmix:CARD=Pro,DEV=0
    FastTrack Pro, USB Audio
    Direct sample mixing device
dmix:CARD=Pro,DEV=1
    FastTrack Pro, USB Audio #1
    Direct sample mixing device
dsnoop:CARD=Pro,DEV=0
    FastTrack Pro, USB Audio
    Direct sample snooping device
dsnoop:CARD=Pro,DEV=1
    FastTrack Pro, USB Audio #1
    Direct sample snooping device
hw:CARD=Pro,DEV=0
    FastTrack Pro, USB Audio
    Direct hardware device without any conversions
hw:CARD=Pro,DEV=1
    FastTrack Pro, USB Audio #1
    Direct hardware device without any conversions
plughw:CARD=Pro,DEV=0
    FastTrack Pro, USB Audio
    Hardware device with all software conversions
plughw:CARD=Pro,DEV=1
    FastTrack Pro, USB Audio #1
    Hardware device with all software conversions