Can I output music from an iMac through my surround sound system using AppleTV via my home wireless network?

I have a surround sound system which includes a TV, audio system and apple TV (version 1). My goal is to be able to output music through apple TV via my wireless network. For example, I'd like to create a playlist on my imac and then output it through Apple TV and thus my surround sound system. Hopefully I can use the equipment I already have without spending a fortune to make this happen. Thanks for any assistance.

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