I want to enter the field of music audiophiles and I want to get the basics of how one can benefit from a sound card? I recently purchased the Asus Xonar Essence STX for cheap for cyber monday and I set it up on my computer. I have the Logitech Z623 speakers and....don't really notice the difference. I have yet to purchase a pair of headhones from maybe Sennheiser or Audio-Technica. Can someone break it down for me how it is beneficial and whether you own one and which one?