$ amixer controls
numid=20,iface=CARD,name='Headphone Jack'
numid=19,iface=CARD,name='Internal Mic Phantom Jack'
numid=18,iface=CARD,name='Mic Jack'
numid=21,iface=CARD,name='Speaker Phantom Jack'
numid=17,iface=MIXER,name='Master Playback Switch'
numid=16,iface=MIXER,name='Master Playback Volume'
numid=2,iface=MIXER,name='Headphone Playback Switch'
numid=1,iface=MIXER,name='Headphone Playback Volume'
numid=24,iface=MIXER,name='PCM Playback Volume'
numid=13,iface=MIXER,name='Mic Boost Volume'
numid=7,iface=MIXER,name='Mic Playback Switch'
numid=6,iface=MIXER,name='Mic Playback Volume'
numid=11,iface=MIXER,name='Capture Switch'
numid=9,iface=MIXER,name='Capture Volume'
numid=5,iface=MIXER,name='Loopback Mixing'
numid=8,iface=MIXER,name='Auto-Mute Mode'
numid=15,iface=MIXER,name='Beep Playback Switch'
numid=14,iface=MIXER,name='Beep Playback Volume'
numid=25,iface=MIXER,name='Digital Capture Volume'
numid=12,iface=MIXER,name='Inverted Capture Switch'
numid=10,iface=MIXER,name='Inverted Capture Volume'
numid=4,iface=MIXER,name='Speaker Playback Switch'
numid=3,iface=MIXER,name='Speaker Playback Volume'
numid=23,iface=PCM,name='Capture Channel Map'
numid=22,iface=PCM,name='Playback Channel Map'
$ amixer scontents
Simple mixer control 'Master',0
Capabilities: pvolume pvolume-joined pswitch pswitch-joined
Playback channels: Mono
Limits: Playback 0 - 64
Mono: Playback 52 [81%] [-12.00dB] [on]
Simple mixer control 'Headphone',0
Capabilities: pvolume pswitch
Playback channels: Front Left - Front Right
Limits: Playback 0 - 64
Mono:
Front Left: Playback 64 [100%] [0.00dB] [on]
Front Right: Playback 64 [100%] [0.00dB] [on]
Simple mixer control 'Speaker',0
Capabilities: pvolume pswitch
Playback channels: Front Left - Front Right
Limits: Playback 0 - 64
Mono:
Front Left: Playback 0 [0%] [-64.00dB] [off]
Front Right: Playback 0 [0%] [-64.00dB] [off]
Simple mixer control 'PCM',0
Capabilities: pvolume
Playback channels: Front Left - Front Right
Limits: Playback 0 - 255
Mono:
Front Left: Playback 255 [100%] [0.00dB]
Front Right: Playback 255 [100%] [0.00dB]
Simple mixer control 'Mic',0
Capabilities: pvolume pswitch
Playback channels: Front Left - Front Right
Limits: Playback 0 - 31
Mono:
Front Left: Playback 0 [0%] [-34.50dB] [off]
Front Right: Playback 0 [0%] [-34.50dB] [off]
Simple mixer control 'Mic Boost',0
Capabilities: volume
Playback channels: Front Left - Front Right
Capture channels: Front Left - Front Right
Limits: 0 - 3
Front Left: 0 [0%] [0.00dB]
Front Right: 0 [0%] [0.00dB]
Simple mixer control 'Beep',0
Capabilities: pvolume pswitch
Playback channels: Front Left - Front Right
Limits: Playback 0 - 31
Mono:
Front Left: Playback 0 [0%] [-34.50dB] [off]
Front Right: Playback 0 [0%] [-34.50dB] [off]
Simple mixer control 'Capture',0
Capabilities: cvolume cvolume-joined cswitch cswitch-joined
Capture channels: Mono
Limits: Capture 0 - 31
Mono: Capture 20 [65%] [13.50dB] [on]
Simple mixer control 'Auto-Mute Mode',0
Capabilities: enum
Items: 'Disabled' 'Enabled'
Item0: 'Enabled'
Simple mixer control 'Digital',0
Capabilities: cvolume
Capture channels: Front Left - Front Right
Limits: Capture 0 - 120
Front Left: Capture 60 [50%] [0.00dB]
Front Right: Capture 60 [50%] [0.00dB]
Simple mixer control 'Inverted',0
Capabilities: cvolume cvolume-joined cswitch cswitch-joined
Capture channels: Mono
Limits: Capture 0 - 31
Mono: Capture 0 [0%] [-16.50dB] [off]
Simple mixer control 'Loopback Mixing',0
Capabilities: enum
Items: 'Disabled' 'Enabled'
Item0: 'Disabled'