The quick version: It's crap. Pass.
If you need an inexpensive stand-alone S/PDIF DtoA, there's a FiiO that people seem to like, that runs around $30 on Amazon. Gefen makes a similarly sized version that can also decode Dolby Digital, which sells for around $90. You could also scour ebay for D/A converters from yesteryear, like the Technics SH-AC500D or the various Sony and Yamaha competitors. Finally, if you're talking about hooking up to a PC, there's an ocean of USB, PCI, PCIe, FireWire, etc audio controllers out there that you can (and should) look at. A lot of them include headphone amplifiers too.