Hello,
This is a very serious issue, the HTML5 audio tag doesn't work anymore. Try this page for instance that worked well in IE on Windows 8.1:
http://www.jplayer.org/HTML5.Audio.Support/
In IE, I now get "Invalid Source" and in Spartan "This type of audio file isn't supported".
It blocks my application "Clouder!" from playing any track, and I can't play anything from soundcloud.com either
This is a severe regression!
Fabien