[alsa-devel] Problem getting USB DAC to work

[Alan Stern]

On Mon, 11 Jul 2016, John Westwood wrote:

> I think the MTP stuff is a red herring. I checked syslog when I use a DAC that
> works (Audiolab MDAC) and that has the MTP lines too, but it doesn't have the
> warning line about Unlikely big volume range.
> 
> In addition, the working DAC has the following lines which are not present the
> non-working DAC:
> 
> Jul 11 19:56:35 atlas kernel: [83940.049124] input: Lakewest Audio Audiolab
> M-DAC as /devices/pci0000:00/0000:00:1d.1/usb7/7-2/7-2:1.0/0003:0451:
> ADAC.0002/input/input12
> Jul 11 19:56:35 atlas kernel: [83940.104367] hid-generic 0003:0451:ADAC.0002:
> input,hiddev0,hidraw1: USB HID v1.11 Device [Lakewest Audio Audiolab M-DAC] on
> usb-0000:00:1d.1-2/input0
> 
> With the non-working DAC I get these lines instead:
> 
> Jul 11 19:56:25 atlas kernel: [83930.079063] usb 7-2: Warning! Unlikely big
> volume range (=65535), cval->res is probably wrong.
> Jul 11 19:56:25 atlas kernel: [83930.079067] usb 7-2: [2] FU [PCM Playback
> Volume] ch = 1, val = -32768/32767/1
> 
> 
> I think maybe the problem is similar to this one:
> 
> https://groups.google.com/forum/#!topic/linux.debian.kernel/HwwkRkbL5aY
> 
> Is my problem a bug in snd-usb-audio? Or am I doing something wrong? I would
> really appreciate some thoughts on this, I feel like I'm talking to myself :-(

Considering that you're not really doing anything, you're probably not 
doing something wrong.  :-)

On the other hand, you're likely to get more of a response if you 
direct your questions to the person who solved the problem mentioned in 
that Debian bug report, and if you CC: the sound developers' mailing 
list rather than the general USB list.

Alan Stern