I have 2 USB DACs. One uses a Burr-Brown chip and the other one is a Modi 3+ (custom circuit) from Schiit Audio. Both work under Linux. The Schiit seems to accept playback data but no analog output appears. Both are claimed by uaudio(4).
Note the lack of a outputs.dac= line for the unhappy unit. There are quite a few differences in the USB interface information especially V1 vs V2 format. Is this problem discussed in an online thread somewhere or would tech@ be interested? I'm not familiar with the details of USB audio (yet). Would defining UAUDIO_DEBUG help? Attaching: uaudio0 at uhub3 port 3 configuration 1 interface 1 "Schiit Audio Schiit Modi 3+" rev 2.00/1.00 addr 5 uaudio0: class v2, high-speed, async, channels: 2 play, 0 rec, 1 ctls audio1 at uaudio0 uaudio1 at uhub3 port 4 configuration 1 interface 1 "Burr-Brown from TI USB Audio CODEC" rev 1.10/1.00 addr 6 uaudio1: class v1, full-speed, sync, channels: 2 play, 2 rec, 3 ctls audio2 at uaudio1 uhidev3 at uhub3 port 4 configuration 1 interface 3 "Burr-Brown from TI USB Audio CODEC" rev 1.10/1.00 addr 6 uhidev3: iclass 3/0 ucc0 at uhidev3: 3 usages, 3 keys, enum wskbd2 at ucc0 mux 1 wskbd2: connecting to wsdisplay0 mixerctl -f /dev/audioctl1 <--------------------------| outputs.dac_mute=off | record.enable=sysctl | | mixerctl -f /dev/audioctl2 | outputs.dac=255,255 <--------| outputs.dac_mute=off record.enable=sysctl Linux usbdevs output: T: Bus=01 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 3 Spd=12 MxCh= 0 D: Ver= 1.10 Cls=00(>ifc ) Sub=00 Prot=00 MxPS= 8 #Cfgs= 1 P: Vendor=08bb ProdID=2902 Rev=01.00 S: Manufacturer=Burr-Brown from TI S: Product=USB Audio CODEC C: #Ifs= 4 Cfg#= 1 Atr=80 MxPwr=100mA I: If#= 0 Alt= 0 #EPs= 0 Cls=01(audio) Sub=01 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=02(O) Atr=09(Isoc) MxPS= 192 Ivl=1ms I: If#= 2 Alt= 1 #EPs= 1 Cls=01(audio) Sub=02 Prot=00 Driver=snd-usb-audio E: Ad=84(I) Atr=05(Isoc) MxPS= 196 Ivl=1ms I: If#= 3 Alt= 0 #EPs= 1 Cls=03(HID ) Sub=00 Prot=00 Driver=usbhid E: Ad=85(I) Atr=03(Int.) MxPS= 1 Ivl=10ms T: Bus=03 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#= 7 Spd=480 MxCh= 0 D: Ver= 2.00 Cls=ef(misc ) Sub=02 Prot=01 MxPS=64 #Cfgs= 1 P: Vendor=30be ProdID=1014 Rev=01.00 S: Manufacturer=Schiit Audio S: Product=Schiit Modi 3+ C: #Ifs= 2 Cfg#= 1 Atr=80 MxPwr=500mA I: If#= 0 Alt= 0 #EPs= 0 Cls=01(audio) Sub=01 Prot=20 Driver=snd-usb-audio I: If#= 1 Alt= 3 #EPs= 2 Cls=01(audio) Sub=02 Prot=20 Driver=snd-usb-audio E: Ad=01(O) Atr=05(Isoc) MxPS=1024 Ivl=125us E: Ad=81(I) Atr=11(Isoc) MxPS= 4 Ivl=1ms
