The site Karaoke Version is pretty good place to get kind of what you are looking for. You can choose to customize the MP3 backing track exactly as you want it. You can even adjust the key within limits. I have used it once or twice and the results were what I was expecting and at a cost of 2 to 3 dollars per file, it is not too expensive. visit the site, pick a song, choose if you want guitar backing tracks, etc. you can experiment for free with a snippet of any song they have.

Not exactly what you were talking about but could be a resource for you. Otherwise the Norton fake disks are good, midi styles will allow you to adjust as you see fit and create very good reasonable facsimiles of any song you wish.

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