The damn thing works. It works both on SPDIF/coax input using my CD player as a transport into my supposedly magical jitter-irrelevant ASRC enhanced wonder DAC, and on the Toslink output from the TV fed by USB inputs from a Roku, a blu ray player, and a video game console into that same DAC. But it doesn’t do both at the same time.
If you want to use both SPDIF and Toslink sources at the same time without flopping cables around, you’ll need two of these little turds. But it does work. The level and kind of improvement is similar to a power supply upgrade to a preamp or turntable.