When I wrote the above, I was on my iPhone, so I was brief. The HE-560 is clearly better than an entry level headphone. I find it to be just a touch heavy, but quite comfortable. I listened to it a lot when I first got it, and it was a gift from my better half, so I’ll never sell it. Over the course of the versions, the HE-560 has had some quality issues, with a few people experiencing driver failures. I’ve been lucky with mine.
The Sennheiser HD-6xx gets listened to as much because it is a known standard quantity as anything else, but I find that when I do listen to it, I like it. I keep it on my main rotation, driven by a Lyr3 and Bifrost 2/64. If I plug the Hifiman HE-560 into that combination, it is clearly better overall than the Senn. The FQ is more even, bass extended, significantly more air, and faster. But that station is also where I have the STAX SRM-T1S coming out of the balanced side of the Bifrost 2/64, and the Nectar Hive headphones, which are lighter, faster, and similar in overall sound to the HE-560. They are preferred.
I sometimes plug the RAD-0 into this combination, but I keep the Rossons in their case, and often listen to them in a different location. As one would expect, the Rosson’s are a good cut above, not in the same class as the HE-560. When I got the HE-560, they listed at $999 and were on sale for a bit over $700. The Rosson was over $2200 new. Much more than I’d ever paid for a headphone.
I still think that the GRADO RS-1e (Now RS-1x) is an extremely worthy choice, and valid in it’s price range, especially with the Beautiful Audio pads. Most who have heard them agree. They’re light, comfortable, have great soundstage. Bass is stronger and deeper than people expect, and the Beautiful Audio pads change them from the on-ear to an over ear.
I have not listened to many of the other headphones like the AEON Open so I can’t give any opinion. All I’m trying to do is to give you a better feeling for the HE-560.