[BillyH]

Hello forum!

I've been trying my best to get my Sound Devices USBPre2 working as a USB Audio Class 2.0 device.

Others have managed this issue on other SD interfaces using USB_Modeswitch:
https://linuxmusicians.com/viewtopic.php?t=26160
https://llllllll.co/t/opinions-on-sound ... 6/17529/67

Unfortunately, I've been consistently running into error -5 when trying this for my model:

Code: Select all

$ sudo usb_modeswitch -v 0x0926 -p 0x0202 -W -u 2
[sudo] password for billy:
Take all parameters from the command line


 * usb_modeswitch: handle USB devices with multiple modes
 * Version 2.6.1 (C) Josua Dietze 2017
 * Based on libusb1/libusbx

 ! PLEASE REPORT NEW CONFIGURATIONS !

DefaultVendor=  0x0926
DefaultProduct= 0x0202
Configuration=0x02

Look for default devices ...
  found USB ID 1d6b:0003
  found USB ID 1a40:0101
  found USB ID 0489:e0cd
  found USB ID 0926:0202
   vendor ID matched
   product ID matched
  found USB ID 1d6b:0002
  found USB ID 18d1:4eeb
  found USB ID 1d6b:0003
  found USB ID 06cb:00bd
  found USB ID 04f2:b6d9
  found USB ID 2a39:3fb0
  found USB ID 1d6b:0002
 Found devices in default mode (1)
Access device 006 on bus 003
Get the current device configuration ...
Current configuration number is 1
Use interface number 0
 with class 1

USB description data (for identification)
-------------------------
Manufacturer: Sound Devices
     Product: USBPre2
  Serial No.: HB0812114018
-------------------------
Change configuration to 2 ...
Looking for active drivers ...
 OK, driver detached
 OK, driver detached
 OK, driver detached
 OK, driver detached
 Configuration was reset
 Changing the configuration failed (error -5). Try to continue
-> Run lsusb to note any changes. Bye!

The device remains unchanged under lsusb but remains unresponsive until reboot.
Switching the configuration back to 1 doesn't work either (until reboot):

Code: Select all

$ sudo usb_modeswitch -v 0x0926 -p 0x0202 -u 1
Look for default devices ...
 Found devices in default mode (1)
Access device 006 on bus 003
Get the current device configuration ...
 Determining the active configuration failed (error -5). Abort

This behavior spans different machines with different distros and kernels. I've also tried this with similar udev rules to those in the links above.
Any help would be massively appreciated. Getting the interface to operate as a UAC 2 device would allow me to record in higher sample rates.

Many thanks ^_^