USB DAC for Pro Audio PC Application

Today at church the special music reminded me of how bad things sound when played from the computer.  In this case it was an mp3 file.  I don't know much the sound card in the computer, but am thinking that getting a USB DAC might improve the sound quality.  It's not a fancy system and a relatively small church, but if I could improve it by adding a budget USB DAC it would comfort my ears.

Here's the list that I've started:

Audioquest Dragonfly Black - $130

Audioengine D3 - $99

Fosi Audio DS2 - $60

Creative Labs Sound Blaster - $20

I don't need anything but the DAC, any suggestions/recommendations?  At this point I'm leaning towards the $20 option to test the theory of it making a difference.