Spotify is finally ready to enter the world of mainstream advertising, airing ads during NBC’s The Voice in an effort to expand on its 6 million paying subscribers. These 6 million put Spotify handily ahead of competitors like Rdio and MOG, but the future of the streaming model supporting these services is far from perfect, and music industry criticism of the financial repercussions of a subscription model could result in more than just grumbling in coming years. The old rumor that Spotify aims to become an all-in-one destination for all forms of media online – one to compete with Netflix and Hulu – has gained new breath in light of this ad push. Could Spotify be gearing up to take new ground, and potentially silence its most vocal critics by balancing its financial woes in the process?