USB Audio device: Shure MV7 not recognized

[GitHub issues - edited]

alsa-project/alsa-lib issue #98 was edited from vchuravy:

Hello! i hope this is the right venue for reporting not working audio devices.

```
> alsa-capabilities
9: `USB Audio' Digital USB Audio Class audio output on device Shure MV7
    -hardware address:               hw:3,0  (or hw:MV7,0)
    -device label:                   Shure MV7
    -formats:                        (n/a)
    -usb audio class:                UAC2 (isochronous asynchronous)
    -streamfile:                     /proc/asound/card3/stream0
    -character device:               /dev/snd/pcmC3D0p
    -monitor file:                   /proc/asound/card3/pcm0p/sub0/hw_params
```

`alsa-info.sh`: http://alsa-project.org/db/?f=7bfa1d9ac09aac53a52834e95b833d299dfe3896
`pulseaudio -vvv` https://gist.github.com/vchuravy/f5f8ee972d5e2179387c8c53423379f6

During the pulseaudio session I plugged the device in and then unplugged it. I am happy to dig in, but I would need some guidance on where to start. As a side-note the microphone seems to work on Android so I am wondering if they are using a different driver.

The device has a head-phone jack with feedback from the mic, and without pulseaudio running I hear the microphone inputs.
So I was wondering if this was in particular a pulseaudio issue.

```
> arecord -l
**** List of CAPTURE Hardware Devices ****
card 1: Generic [HD-Audio Generic], device 0: ALCS1200A Analog [ALCS1200A Analog]
  Subdevices: 0/1
  Subdevice #0: subdevice #0
card 1: Generic [HD-Audio Generic], device 2: ALCS1200A Alt Analog [ALCS1200A Alt Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 2: C925e [Logitech Webcam C925e], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 3: MV7 [Shure MV7], device 0: USB Audio [USB Audio]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

> arecord -d 3  -f U8 sample.mp3
ALSA lib pcm_dsnoop.c:638:(snd_pcm_dsnoop_open) unable to open slave
arecord: main:830: audio open error: No such file or directory
```

Issue URL     : https://github.com/alsa-project/alsa-lib/issues/98
Repository URL: https://github.com/alsa-project/alsa-lib