I have two units that do the same. The first is a Theta Timebase Linque Conditioner that is both a jitter reducer as well as converts toslink to SPIDF. It has an optical and SPIDIF input and SPIDIF only output. It runs used from $130-$250. The second is the Genesis Digital Lens which is an entirely different animal. I won't go into explanations except that it reclocks and eliminates transport jitter. It also has multiple input and output types. I love the lens and it improved my system greatly. Do a search on Agon for any of these units for more detailed analysis.
Good hunting