This one is cheaper at $11, but only offers 120ohm and 240ohm. (you could ask them if they do 150ohm too)
I think 150ohm would be closer to bring 64ohm to 200ohm.
I've owned and used several of these things before (51, 150, 300 ohm). No way this will turn your headphones into a "High Edition". I can't say I paid too close attention to any changes in sound and I didn't notice anything really, but certainly nothing dramatic or that sounds like you've upgraded or something. If anything it's possible it would just make the sound worse as apparently these adapters actually raise the output impedance of your amp.
By the way, if anyone was planning to buy one of these, don't go for the cheaper ones made by "wemakeamp." Build quality is quite sub par IME.
Edited by manveru - 6/16/12 at 10:39pm