I can only speak for R9 and it's very comfortable, no issues.

R9 has more bass, it extends deeper, it hits harder and it's very detailed and textured compared to Robin.

They are huge, but the paint job is really nice though, it's sparkly like new car. You would look weird as fuck while wearing these outdoors.

Not at this price but I've sivga Robin sv021. It's $150.

I've been using them for sometime and I think they're underrated closed back. I bought these at $350 but with custom taxes and shipping to get these to India I ended up paying $473.

After I started listening to them I thought these would benefit from a balanced cable so I paid another $85 to get a balanced cable. Actually running them balanced makes them sound better, there is a significant amount of increase in clarity and you get more, better and controlled bass, midrange gets more forwarded and vocals sound clearer. With balanced connection it's usually better seperation and dynamics but this headphone requires balanced to absolutely sound their best.

The general sound signature is very warm but also natural, these stay away from bright treble very smooth and soft in that area, great for longer listening periods. It's a v shape tuning so you are not going to do analytical listening, these don't have full bodied sound that you get with something that has more midrange. These are just fun and they're super fun to listen to.

The bass is prominent and a highlight of this headphone, the bass will rumble very hard and if you keep making them louder they'll literally shake on your head, it extends into deep sub bass levels. Treble never crosses the line of being sharp while being very detailed very clean and clear.

As you can tell by looking at the picture these are huge, they have massive cups so the soundstage also sounds huge and very wide and holographic too, I'd say depth could be even better but sounds come from everywhere.

These can produce a lot of details without being analytical I haven't heard anything at this price so I do not know if these are technically as good as other hifiman line up at this price but I'm sure these are very competent.

The build quality is good although they could've made using wooden cups instead of plastic, the pads are soft and comfortable.

So yeah I'd say at this price point even after paying taxes and paying extra for a balanced cable I'd say these are worth it just for pure enjoyment listening they can make everything sound great. They can make Spotify sound like you're listening to flac and a youtube video sound like Dolby Atmos they're absurdly fun you'll never get bored even after hours and hours of continuous listening. I'm sorry if this is too long I just want to be thorough.