Simply put, SIRA fundamentally redefines copyright and fair use in the digital world. It would require all incidental copies of music to be licensed separately from the originating copy. Even copies of songs that are cached in your computer's memory or buffered over a network would need yet another license. Once again, Big Copyright is looking for a way to double-dip into your wallet, extracting payment for the same content at multiple levels.
The link is to the post and discussion on ipaction.org.