Rdio, the unlimited, on-demand social music service from the founders of Skype, today announced they have raised a new financing round in the amount of $17.5 million from new and existing investors.

Rdio’s social music service brings music alive by letting subscribers listen to as many songs as they want, anytime, anywhere, and discover and share new music with friends.

The latest round adds Mangrove Capital Partners to an impressive roster of investors that includes Rdio co-founder, Janus Friis, through his investment entities, as well as Atomico and Skype.

Rdio intend to use this infusion of funds to aggressively expand its footprint to new platforms and new regions in 2011. Part of the funds will also go towards hiring new talent, expanding outreach efforts to consumers, and continuing to innovate on new ways to bring the social music experience to music lovers.

“We are changing the way we find and listen to music. Anything and everything is instantly available from any computer and phone and easily shared with our friends. The days of expensive music downloads are coming to an end,” said Janus Friis, Rdio co-founder.