Google Chrome	63.0.3239.20 (Official Build) dev (32-bit)
Revision	0
Platform	10032.17.0 (Official Build) dev-channel bob
Firmware Version	Google_Bob.8785.226.0
Customization ID	ASUS-BOB

What steps will reproduce the problem?
(1) Sign in to the device.
(2) Play any youtube video.
(3) plug iMicro (SP-IM320) USB headset.
(4) Decrees the volume level (press F9 key) to bellow 45%.

What is the expected result?
Audio should be gradually lowered 

What happens instead?
USB audio stopped after 45% 

Note:
This issue is specific to the combination of BOB and iMicro (SP-IM320) headset.
  --Not able to reproduce this issue on bob with Microsoft USB head set.
  --Not able to reproduce this issue on wolf with  iMicro (SP-IM320) headset.