Get the audio necessarily as without it you won't understand much of the place. Important to visit once in Phnom Penh, gives you a big chunk of the history to think about.
Had an amazing time traveling australia, and ended up going to see this spectaular rock i think the most stunning thing for me was seeing the differnt colours change on the rock as the sun went around and up and down changeing from blue to green to yellow even to the extreme of pinks amazing place everybody should visit