SPKR OUT VS LINE OUT ( Which is Noisier?)

I compare the Output and the noise produced from the Speaker Out and Line out. During my testing I realized I was getting a constant hiss from the cards whether they were powered or not. Maybe you can suggest a way to eliminate this extra noise. I created 3 new FM synthesis tracks with "David's ISA Audio Board" thanks to a kind "friend of the channel" that lent it to me to make this video.