Announced earlier in the year, has launched its iTunes-rivaling music download service into public beta in the States.

Claiming to be "working to make this absolutely the best place to buy music" the company has highlighted several reasons for sign-up.

The current offering comes in at 2,000,000 songs from both independent and major record labels, including EMI, which will be added to on a daily basis.

The songs offered via Amazon will all be DRM-free, so they will play on any device the customer wants to play them on, and they will be encoded at 256kbps which offers higher audio quality than standard downloads.

Unlike iTunes, that charges a premium for DRM-free music, at Amazon, tracks are priced from 89 cents for a single song and from $4.99 for an album.

It will be interesting to see the user feedback from this public beta. Amazon is the world's largest retailer for music CDs and industry insiders have speculated that if anyone can challenge iTunes' dominance, it's Amazon.