Comment 6 for bug 1384952

post the output

lsusb -vvvv

it is strange that there is no device zero

have you try device 1 ?

ARECORD

**** List of CAPTURE Hardware Devices ****
card 1: Ed [Xonar U7 Echelon Ed.], device 1: USB Audio [USB Audio #1]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

Simple mixer control 'PCM',0
  Capabilities: cswitch cswitch-joined
  Capture channels: Mono
  Mono: Capture [on]
Simple mixer control 'PCM Capture Source',0
  Capabilities: enum
  Items: 'Unit 22' 'Unit 22'
  Item0: 'Unit 22'
Simple mixer control 'PCM',1
  Capabilities: cswitch cswitch-joined
  Capture channels: Mono
  Mono: Capture [on]
Simple mixer control 'IEC958 In',0
  Capabilities: pswitch pswitch-joined
  Playback channels: Mono
  Mono: Playback [on]
Simple mixer control 'Input Gain Pad Control',0
  Capabilities: pswitch
  Playback channels: Front Left - Front Right
  Mono:
  Front Left: Playback [on]
  Front Right: Playback [on]