With the help of the Fedora Copr Project [1] I've made available
builds of Audacious 3.5-alpha1 for Fedora 20 and Rawhide:
https://copr.fedoraproject.org/coprs/mschwendt/audacious-next/
On the way to Audacious 3.5 the Plugin API is incompatible with the older
Audacious in F20 already, so don't hope for being able to install prebuilt
non-free plugin packages since you will face unresolvable dependencies.
As always, whether and when to continue with this next Audacious in the
official Rawhide (F21 development) repo, depends on feedback, further
testing and upstream changes.
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[1]
https://fedorahosted.org/copr/