Hi,
Version: 2.513
USB Dac: Topping D50
Hardware device: Allo USBridge w/ Sparky board
Kernel version: 3.10.38 armv7l
Volumio is not detecting my USB dac. I have checked “aplay -l” and “lsusb” and cannot see the device in the output. Shairport is not functioning. But, Roon Bridge is detecting the device and automatically outputting to the DAC.
I tried a factory reset to test if Roon Bridge plugin was conflicting and it did not make a difference.
Any advice would be much appreciated.
Luckily this is not a bug, you might just have the wrong volumio version 
Roon is based on a totally different kernel, so it is very well possible they added Topping D50 or use a version where D50 is supported as a standard.
We have had discussions about D50 and Sparky a few times before.
For Allo it depends on when your image was built, please check your “/etc/os-release” as we don’t have that version anymore.
Sparky has an old kernel, but I know that Allo updated the kernel at the beginning of this year (2019-01-04) and added quite a list of DSD capable devices.
In case your image was built before 2019-01-04, Topping won’t work.
Anyway, I think you’re on an old version, I would go to the download page and get the latest (2.672), or update through the system menu.