MPEG Streamclip can play directly at 2x, but not 1.5x. With some practice, it is understandable. Unlike QuickTime Player, it does not keep the pitch the same, so you have to use Audio Hijack Pro
<http://www.rogueamoeba.com/audiohijackpro/>
with the Apple AUPitch effect set to -1,000 to get the pitch back to normal. (If you aren't recording, you can use it in its free trial mode.)