The Plantronics .Audio 510 USB headset (Vendor=047f ProdID=c001) seems to have certain output levels issues with drivers in 2.6.23-rc2-mm2 (at least). In particular, setting

amixer -c 1 sset PCM 3

results in no output, while

amixer -c 1 sset PCM 4

results in levels that are somewhat loud for applications tested. Volume appears to be roughly linear in the range above PCM=4, if loud for applications tested.

The USB ID information (Vendor=047f ProdID=c001) doesn't seem to be noted as exceptional by any driver code in the 2.6.23-rc2-mm2 kernel, and web searches for 'plantronics' or 'audio 510' and linux or alsa seem to return little pertinent information. What would be most useful to try next?

Various outputs follow:

$ amixer -c 1 Simple mixer control 'PCM',0 Capabilities: pvolume pswitch pswitch-joined Playback channels: Front Left - Front Right Limits: Playback 0 - 151 Mono: Front Left: Playback 6 [4%] [-27.29dB] [on] Front Right: Playback 6 [4%] [-27.29dB] [on] Simple mixer control 'Mic',0 Capabilities: cvolume cswitch cswitch-joined Capture channels: Mono Limits: Capture 0 - 16 Mono: Capture 14 [88%] [21.00dB] [on] Simple mixer control 'Auto Gain Control',0 Capabilities: pswitch pswitch-joined Playback channels: Mono Mono: Playback [on]

$ cat /proc/bus/usb/devices

T: Bus=05 Lev=01 Prnt=01 Port=01 Cnt=01 Dev#= 6 Spd=12 MxCh= 0 D: Ver= 1.10 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs= 1 P: Vendor=047f ProdID=c001 Rev= 1.00 C:* #Ifs= 4 Cfg#= 1 Atr=a0 MxPwr=100mA I:* If#= 0 Alt= 0 #EPs= 0 Cls=01(audio) Sub=01 Prot=00 Driver=snd-usb-audio I:* If#= 1 Alt= 0 #EPs= 0 Cls=01(audio) Sub=02 Prot=00 Driver=snd-usb-audio I: If#= 1 Alt= 1 #EPs= 1 Cls=01(audio) Sub=02 Prot=00 Driver=snd-usb-audio E: Ad=01(O) Atr=09(Isoc) MxPS= 200 Ivl=1ms I:* If#= 2 Alt= 0 #EPs= 0 Cls=01(audio) Sub=02 Prot=00 Driver=snd-usb-audio I: If#= 2 Alt= 1 #EPs= 1 Cls=01(audio) Sub=02 Prot=00 Driver=snd-usb-audio E: Ad=82(I) Atr=05(Isoc) MxPS= 100 Ivl=1ms I:* If#= 3 Alt= 0 #EPs= 1 Cls=03(HID ) Sub=00 Prot=00 Driver=usbhid E: Ad=83(I) Atr=03(Int.) MxPS= 4 Ivl=32ms