There are free course materials from MIT available online here: MIT open courseware
For those of you who aren't aware, MIT is a private school in Massachusetts that is lucky to be decent academically because they aren't known for sports.
For example: a lecture video series on system feedback: http://ocw.mit.edu/resources/res-6-010-electronic-feedback-systems-spring-2013/course-videos/
All of the resources needed to understand the fundamentals of sound reproduction are available freely at your fingertips! There is no excuse for any sort of nonsense like "but science doesn't explain everything!" or "we can hear things that can never be measured!" Well, here is a free undergraduate level education in the principles required to understand the physics of audio play back---from digital storage to the mechanics of sound.