First time poster, got MusicBee for the first time last night and been reading up like crazy. Steven, you should be proud, about as happy with MusicBee as I have ever been with an audio player.
Anyway, back on topic and IF you have a Creative sound card: I had ridiculously distorted bass. Was looking at everything from poor quality files, sound drivers, EQ settings, and finally resetting all the settings in my Creative Sound card. The thoughts on the EQ here are interesting as well, but I took them to heart.
I found that after hitting the default settings button in the creative mixer/config/whatver app, Windows Media player sounded WAY better and it had its EQ settings all jacked up for dance/techno. MusicBee also sounded a little better, I knew I was making progress. I eventually found in MusicBee under the Player section in Preferences (Ctrl-O) that changing the output from DirectSound to ASIO was a night and day difference. The sound device for me changes to "Creative ASIO", I also selected hardware mixing, and 32bit output for the heck of it... not sure what it does.
Obviously not everyone has a Creative sound card (I have an X-Fi Fatality), but I wanted to share in case some do. I can also wildly change around my EQ settings and things are good. I'm not sure why DirectSound sounds terrible and I would assume that Windows Media player probably uses DirectSound for compatibility sake. Also, I never noticed distortion in Battlefield 4 or other games, so in general I am overly perplexed.