To enjoy their gear, high end audio enthusiasts have generally been trapped at home. From speakers, to receivers and amplifiers, none of the means of reproducing quality sound were exactly portable. Even the enthusiast-level headphones that have arrived on the scene over the last few years are large, unwieldy, unfashionable, and require at minimum a decent headphone amp to function. (See: most Audeze, Oppo HA-1, HiFi Man, etc.)
In addition, most planar magnetic headphones are open-backed, which means listening in less-than-quiet or public situations can be a challenge. Well, my fellow audio recluses, the PM-3 by Oppo aims to change all that.