Rumours are growing that Spotify is finally ready to make its step to the United States, with the news that the music streaming service's founder, Daniel Ek, will headline the South by South West conference this year.

SXSW is one of the biggest internet conference/festivals in the US, and the keynote in March next year would seem to fit into line with the growing belief that the time is ripe to take Spotify across ti the US.

Ek has made it clear that a US expansion will happen at some point, although it is the lengthy negotiations that make the move more difficult for a service which started in Sweden and swept across Europe.

Back in February, Ek told TechRadar: "A Spotify launch in the US is absolutely part of our plans, but we want to fully establish ourselves in Europe before that happens."

Free service?

The record labels are understandably wary of embracing a service that could impact their profits, especially the free ad-funded model that made it such a success in countries such as the UK.

Neil Smith of Rhapsody America – a paid for music service - told Reuters: "The reason Spotify blew up so big and so fast was it was free.

"That model isn't going to happen in the U.S. anytime soon, maybe ever. The U.S. is the market where the labels make all their money.

"They can't afford to have a service that doesn't generate substantial revenue suck up all the usage. If it was $15 per month (c£9) out of the gate, it wouldn't have a million users. Once you take the free piece away, we compete pretty well."

Regardless of opinions, it is still less than clear whether Spotify can replicate its success, but anticipation is already high, and should a free model be arrived at it would certainly make a big impact on the US music industry.