Just for giggles , I took a toslink and ran the Direct TV box into the DAC . Sounds like crap .
OP, many reasons why it might "sound like crap" as you put it, but in case you are interested in identifying why.....
.... you may want to consider glass toslink, like this one:
https://silversonic.com/products/digital-cables/glass-master-toslink/
And you may want to check that the correct output (e.g. PCM) is set within your Direct TV box.