I hate the word better. It is different. The HD6XX is well known as being some people’s endgame headphone. I believe M0N from this site still claims it is one of his all time headphones ever.
The HD6XX has some of the most natural timbre and perfect midrange tuning of any headphone ever. It is the benchmark many other headphones are compared against and usually can not match.
It is not that well extended in the treble or bass but for it’s price, it is unbeatable. It also scales with better and better amps and dacs. In addition, it excels with tubes.
I have owned a lot of headphones and have sold a lot of headphones. I have very expensive headphones in my collection yet I could never think about parting with the HD6XX.
In the end, both the Sundara and the HD6XX are both very good headphones. But when it comes to the HIFIMan stuff, I rec other sets other than the Sundara. If you can swing it and find it on sale, get the HE6se V2. BGGAR rates it #2 under the Susvara.
