Its a bit early to give detailed impressions but comparatively, Sundara has a pretty different sound signature, lot airier, more energetic, and clarity is pretty good, perhaps due to being planar, not sure. Amiron are bit laid back, and for some reason, at least my pair which I got, tend to be very SHRILLY at high volumes. At low to mid, they are smooth and enjoyable. I have noticed that the low end is pretty good for an open can, better than Sundara. What I can say for sure about the comfort (of course different people, different head & ear sizes & shapes) is that the Sundara were pretty good (much better compared to my Sennherier 660s) but the Amiron are slightly better. They have very little clamping pressure and weight pretty balanced on your head. Built like a proper high quality German product, they dont creak, like ahem some brands, despite being plastic. As a side note, the Beyerdynamic Impacto Universal DAC I bought together with the Amiron are fantabulous. For being so tiny, they drive the 250 ohm Amiron VERY well. There are supposed to be for Amiron, T1 and 1990 but since the cables coming out of them are left and right channel terminated in standard 3.5mm jacks, I plugged them into my Sony MDR-Z7 headphones and frankly cant tell a difference between them and my 900 dollar Sony PHA-3 dac, albeit, the Sony day does have a better amplifier built in. I listen to my music quite loudly and the Sony DAC is overkill even for me. So the Impact Universal I am keeping for sure. Amiron on the other hand, still undecided whether to ship back to Amazon or not. Need more auditioning. On a side note, I am going to place an order for the Sundara once again today and unless they are again defective, I plan to audition them longer before posting a comparison with the Amiron.