I posted about this a couple days ago with little help as to fixing this issue. The issue is that the audio for some reason sounds muffled whenever I play audio from the computer. I've played around with all Windows settings and OBS settings. Nothing seems to fix it. I think it may be something wrong with OBS seeing as if I have my stream audio playing and play a sound clip, the quality gets increasingly worse from already bad. I think OBS may be trying to adjust the audio quality which is why it sounds bad in the first place. To be honest I have absolutely no idea because I'm not the greatest with computers, and everyone else I know who streams doesn't have this problem. I've attached the log file and a twitch VOD showcasing the terrible audio quality.
Audio: http://www.twitch.tv/cryphon/b/624394589
Log File: https://gist.github.com/9b1dbf1c28ac35093365
Audio: http://www.twitch.tv/cryphon/b/624394589
Log File: https://gist.github.com/9b1dbf1c28ac35093365