Re: M-Audio FT C600 - driver missing control for disabling the Output Gain Knob

[Olivia Mackintosh <livvy@pandaemonium>]

On Fri, May 01, 2026 at 04:10:51PM -0400, simon@mungewell.org wrote:
> Hi all,
> I recently thrifted a C600 for a bargain price, and happily most of the
> functionality is working fine. I did notice a couple of controls (as seen in
> Windows app) are not presented under Linux.
> 
> There is the ability to disable the large Output Gain Knob (on right side of
> the device), which by defaults controls all of the stereo outputs (1/2, 3/4,
> 5/6).
> 
> Snooping the USB bus under Windows I see there is a USB packet sent with a
> bit mapped values to disable gain control of each stereo output. Wireshark
> Caps available if needed/wanted.
> 
> I suspect this is a moderately easy fix, and likely applies to the C400 as
> well. Happy to work with/test patches to get this implement, but I'm not
> experienced with building ALSA.
> 
> Cheers,
> Simon.

Hi Simon,

Congratuations on the thrift! Happy to help where I can as I have some
experience with making alsa controls. You're on the right track having
captured the control values.

There seems to already be c400 controls set up in the mixer_quirks.c
file, so it should be fairly straightforward to adapt this to also
support the c600.

Let me know if you need support in any way.

Olivia