With the UE Personal Reference Monitors (PRM), you get to play headphone designer and dial in exactly the sound you want. Each pair is totally unique: they're built with the individually designed equalization curves that you select, and custom-molded to your ears. My PRMs sound absolutely amazing, but I'm a little biased -- I designed them to please my ears! Every PRM buyer will do the same, and if you totally screw up and hate the result, Ultimate Ears will give you another try. Each PRM is handmade at UE's facilities in California.