The PM-1 are more versatile/less finicky about sources/amps than the HE-6. Better suited for on-the-go.
The Oppos [smooth, luscious, understated and midrange tilted] are nearly the sonic antithesis to the HE-6 [airy, "neutral", direct and (for me) slightly treble leaning].
Strangely, even though I typically subscribe to the "neutral and airy" Head-Fier camp, I have none-the-less developed an affinity for the PM-1.
It could be novelty, but for whatever reason the PM-1 have struck a chord of interest with me at the moment. For orthos, they seem to portray a more subtle "curvature" to their dynamic and come across in a more conical/less "planar" fashion (I hope that makes sense).
With my best gear, I think that the PM-1 are more tonally and/or dynamically complex--especially in the lower midrange/upper bass registers--than the HE-6 [were]. Electric (R&R) guitar and snare/tom-tom hits are a real treat with the PM-1.
Edited by pataburd - 7/8/14 at 9:13am