Trying to find out which browsers support what audio features I found this site: http://caniuse.com/audio

It links to a sound file-format test, where I see Firefox plays only ogg and wav. That made me wonder if one could do mp3 decoding on the browser. It's possible: http://labs.official.fm/codecs/ but it sounds totally broken on Firefox on my Ubuntu.

So no Flashless SoundCloud on my Firefox yet, but it may soon change: https://bugzilla.mozilla.org/show_bug.cgi?id=799318