Live Music Archive (LMA, aka Archive.Org) is a popular Website for music with live recordings and fully authorized by the bands. There are literally thousands of recordings by hundreds of bands to chose from.
Listen to LMA using Sound Mill
To listen to an LMA playlist, Web browse to any LMA recording page. Here is a personal favorite you can try.
Find the "VBR M3U" link on the Web page (Figure 1). It may also be listed as Stream Playlist(VBR) on some pages. The link will have a file extension of .M3U at the end of the link. (look on right-hand side of web page)
Right mouse-click on the link and pick Copy Link Location. (Copies the link to the Windows clipboard)
In Sound Mill, go to File > Import an M3U Playlist of Files > From Weblink.
In the resulting popup dialog, paste the M3U link into the textbox. (Ctrl+V to paste)
A Sound Item will be created for each MP3 file in the playlist. Now you can play the music files just like any other Sound Item -- Play individual tracks or create a Script playlist in the Automator.
You may need to increase the Load Time-Out option to 10-15 seconds to avoid time-out errors.