I don't own the Sundara but have owned the Ananda and Arya. To me the Planar is inbetween the two but closer to the Arya. This could be due to the tonality of the Planar though as the Ananda and Arya have a more elevated treble area. With Oratorys eq, you can make the Planar sound very similar to the Arya. Some people have also compared the Planar to the Sundara and say Sundara is more transparent. But for me personally, I feel that is not the case. It could be maybe their unit has one of the faults many people have commented on, the source they are using or some other strange thing. But I and many others have agreed the Planar has a presentation in its whole sound very similar to the Arya. To explain that further.
Lows on the Planar are a bit more cleaner, faster and a touch more detailed with slightly better texture and separation.
Mids on the Arya are more forward so this gives the percieved touch of more clarity and slightly bit more detail. But the Planar to my ear had more textural nuance, sounding more natural, I could actually hear guitar strings more clearly and overall mids felt more tonaly correct.
Now the treble area is where they differ. The Arya has more energy up top but extension is about the same on the two. But I felt there is more air on the Planar. Detail does pop out a bit more on the Arya but the Planar has the smoother treble and detail in the treble is extremely similar between the two.
Soundstage in width would go to the Arya, height would go to the Planar and depth for me would go to the Planar. But its all very close.
Imaging to me is more precise on the Planar while separation is on par with the Arya.
Now with Oratorys EQ, I feel the Planar becomes very very similar to the Arya, even if you compare both FRs of the two. The Planar with eq and Arya without eq, you'll see how similar they are.
I personally much prefer the Planar over the LCD-X without and with eq. Many people praise the LCD-X but I feel the Planar is a better performer.
So for my 2 cents. How does the Planar compare to the Sundara? No competition. The Planar wins hands down.
Now for build, it's a different story.
I have not had any issues at all with build on the Planar but some others have. So maybe build is overall better on the Sundara.
And for reliability, I'd also say the Sundara has the upper hand. Yes there has been QC issues with them. But the Planar there is just too many unit varients. Different sounds, build quality issues and so on... It's kind of a gammble buying the Planar.
Overall I do feel when the Planar is 100% right with no issues. It's a hella of an insane headphone, sound wise and price to performance wise. And if Avantone ups their game and QC, it could potentially be end game for some. I am one of those people. I find the Planar end game worthy. I truly do. But I will not sugar coat it and say its the best headphone in the world. It has its serious flaws and Avantone need to fix those flaws ASAP.
But damn, I do seriously love my Planars. They are right up there with my Ultrasone Edition 11, Vision ears VE8, LZ A7 and a few others. They do easily compete with some of the best out there. So be it headphones or iems.
I have said on a earlier post. If I had to pick one headphone and those headphones are the Focal Clear, Hifiman Ananda, Hifiman Arya or the Avantone Planar. I'd choose the most expensive headphone. Sell it. Get the Avantone Planar and upgrade my gear for the Planar. I do find them that good
That is my 2 cents. So take it with a grain of salt and overall, the best judge is your ears. But I understand it could be hard to hear the two side by side. But yes for me. The Planar is the more transparent, clearer and detailed of the two.
Thats Oratorys graph of the Avantone Planar and Hifiman Arya. They both are very similar but the Planar has the warmer/darker/neutral treble. You can imagine how easy it would be to eq the Planar and make it sound extremely similar to the Arya. That is what Oratorys eq does.
Here is Avantone Planar and Hifiman Sundara.
Now tell me, which of the two look more similar...