Hello,
Please can you consider my "ALSA: usb-audio: Add quirks for MacroSilicon MS2100/MS2106 devices" patch, with upstream commit ID 6e2c9105e0b743c92a157389d40f00b81bdd09fe for inclusion in all -stable kernels. Apart from the device IDs, it is a copy of the similar existing patch for MS2109 devices, which is already present in -stable kernels.
John Veness