I have spent a few weeks wrestling with this very problem. I have Quad ERA 1s at home (which are just outstanding) and B&Ws for away from home use - specifically P7s and PX7s. The Quads spoiled the P7s for me a little bit because there’s so much more detail… so the PM-3s seemed a natural choice for an ‘away’ upgrade. I have a second hand pair at the moment. In some ways the Oppos definitely outclass the P7s, but there are real downsides. The planar drivers generally dig out the detail much better. But the treble is sometimes rolled off and occasionally harsh with the Oppos. The P7s have better bass. So, I have tried Campfire’s Cascades. Great if you like bass; not so great otherwise. I also tried Austrian Audio Hi-X 60s. These are superb and if I did not have the P7s or Oppos but had compared them, I’d definitely go for the Hi-X 60s. The only real downsides are that they look pretty utilitarian (“tool-like” according to one reviewer) and are very neutral and revealing. Why not stick with them, then? Well, I had two reservations. First, I think they’re a better set of headphones than the Oppos or P7s, but not dramatically better. Secondly, I heard the Aeon Flow 2 Noires which, by contrast, were a massive leap up sound-wise. They’re just not ideal for the street or public transport - more transportable than portable. And of course the cost is much more than the alternatives. When all’s said and done, if you don’t want to refit your Oppos with new pads etc (Oppo UK have been super helpful on that for me), it boils don to the Hi-X60s or the Noires. Good luck in choosing.