I put on Guardians of the Galaxy on my Blu-ray player this morning, and have the movie going in the background while I work. I’m not paying too much attention, but every couple of minutes another great song comes on the soundtrack that sets my toe tapping. That would be the now-famous “Awesome Mix Vol. 1,” the cassette tape bequeathed to Chris Pratt’s Star-Lord by his dying mom. The keepsake, collecting some of the finest pop songs of the late ’70s and early ’80s, formed the spine of Guardians’ soundtrack, and even became a crucial plot point. And at the end of the film, Peter finds “Awesome Mix Vol. 2,” setting up the sequel, coming to theaters next month.