I believe I might have found a solution. I had problems with audio crackling when using amazon prime or other streaming video surface on the internet. I utilized a warranty exchange, and received a new unit. After receiving the new unit I ran all the updates but still had the same problems with crackling during video playback. I attempted to adjust audio setting and roll back the audio drive, but nothing worked. Finally I attempted to adjust internet explorer. I went into desktop mode an opened IE. I opened the IE setting, went the advanced tab, and reset the IE settings to default. I restarted my surface, and low and behold I no longer had any crackling during streaming video playback. I'm not sure if this will solve everyone's problem but it's worth a shot.
Let me know if it works.