There is a "loudness war" going on in the music industry, that makes the music louder, resulting sounding better in most cars, but lowers the music quality, noticeable when playing on a good HIFI. See: http://turnmeup.org/ or google "loudness war".
My idea is that Spotify could help addressing this issue by providing a column named DR+ (Dynamic Range Value).
Music enthusiast that cares about good music quality, could use th is value to ensure the quality of the music is good.
The user could also search for good dynamic range music. I got this Idea after reading this page: http://dynamicrange.de/node/1
I think the future will bring more Dynamic Range music, and Spotify could start this trend. Maybe the future of digital music will allow the music industry to master two versions of the same album, with and without Dynamic Range?
A similar idea has already been suggested here:
http://community.spotify.com/t5/Spotify-Ideas/Loss
Add your kudos there please - the existing kudos here will be added soon! ;)