HE-500 has tons of detail - it just doesn't present those details aggressively in the way dynamic or balanced armature drivers can present it. For that reason switching from an edgy dynamic or BA to the HE-500 Ortho driver, the latter may seem overly soft sounding, muted and even muffled. The more you listen to HE-500 or other great Ortho, the more you begin to realize that it is actually more detailed and more lively than most, if not all dynamic drivers while also being much easier on the ears with its softer attacks. Regarding the claim that HE-500 doesn't get loud enough out of portable devices, I have to say that to my ears HE-500 can be driven to uncomfortable listening levels even with the quietest recordings I have with all of my portable players, even something pretty weak like Sansa Clip. I never listen to music at extreme volumes though and advise against it - you can get the same or even higher listening enjoyment by listening at moderate levels IMO.
I disagree about PRO900 being worth the price. Maybe I didn't spend enough time with them, but I found the sound to be way too aggressive with piercing with metallic highs and boomy, overpowering bass. A completely unnatural, harsh sound to my ears. Maybe these need a good tube amp or some damping mods because they do have great resolution.
