Ed Pearlman over at Musicteachershelper.com  has done a great review of riffmaster pro.

Whatever your level of learning, it’s great to be able to slow down a recording to work with it.  RiffMaster Pro is a new bit of software out (as well as a smartphone app), which I’ve had the opportunity to explore and review for you.  I was impressed, and I suspect you and your students might be as well.

RiffMaster allows you to load a recording from your computer files or from a CD, and select any speed, up to 75% slower or faster, at which you’d like to listen to it, or to work with any portion of it.  You can then, if you wish, save your selection as a new music file at the new speed.  This function does not change the pitch of the music.

You can jump on over and read more here