Headphone help... with more details :-)

If you liked the 57’s then you definitely want to consider phones with a planar magnetic driver. Unfortunately, the price of entry is a little higher. But if you want to try out a vintage planar magnetic (Orthodynamic) for (usually) under $200, keep an eye out on eBay for the Yamaha HP-1 (or YH-1) HP-2 (or YH-2) or (the most expensive) HP-100. I have all three and they beat all my other phones except the fabulous Denon AH-D7000 (which has a regular dynamic driver) -- no longer in production, but worth looking for.

The only caveat with the Yamahas, is they need a bit more power than most (but that’s also true of the new planar magnetics as well.) Here are a couple of links to get you started:

http://www.innerfidelity.com/content/how-planar-magnetic-headphones-work#1o0rS1YKav6iD0y6.97

http://www.head-fi.org/t/111193/orthodynamic-roundup

Thank you so much for the information, now I have a more clear direction.

I remember the Yamaha YHD-1 headphones as my favorite, many years ago. I still have the earpieces but the headband disintegrated prematurely. Since then, I have moved on to the Stax family. It doesn't sound as if you are in the market for megabuck phones (since you are looking at Oppo PM-3, not PM-1) but I would still look into one of the Stax entry-level offerings. Once you listen to Stax, it's hard to settle for dynamic phones. I'm just trying to prevent buyer's remorse. Alternatively, Sony makes some phones that are both comfortable and smooth sounding.