The power box runs Raspbian Jessie, for an ARMv7 CPU.
TPCast have a custom version of USB Network Gate by Eltima. It doesn't support higher the Linux Kernel 4.4 according to the website so this may well be why the microphone doesn't work (see Kernel Issues below).
How do we know it's USBNG? Download their client, open it, run the TPCast software and connect to the brick and watch as the USBNG software detects your connected devices as remote devices.
The Linux Kernel used by the TPCast is version 4.4, which has a bug that causes issues with Isochronous USB devices such as microphones and webcams. It doesn't affect all USB mics and webcams but the Vive's are indeed affected by this.