PC audio setup

Hey guys, I am currently in the middle of creating a new PC "battlestation" as r/battlestations calls it, and I need your help on the audio front.

The equipment I currently have are a set of Pioneer sp-bs41-lr speakers and an old JVC stereo receiver. As of this moment, I just have an audio cable connected directly to the motherboard and I am getting what I believe to be good sound.

I was wondering if there were any extra steps that I should take that would cause a noticeable improvement to the sound quality I am getting (such as an soundcard or a DAC). I was hoping to keep this upgrade to under $100 if that is possible.

Thanks for your help!