Had the pleasure of listening to the Susvara and the SR-009S side by side yesterday. The Susvara was driven by the Viva Egoista 845, the Stax by the Viva Audio Egoista 2A3. Same DAC and source.
I tested them during one of the quieter moments of the show, quickly A/Bed 15secs back to back on several songs, thus these are just quick initial comparative impressions.
I tried on the 009S first, and immediately was struck by the amount of detail being communicated through. The headphone seemed very balanced throughout the frequency range, and exhibited a great sense of air and detail. Almost like the lightest most sumptuous fluff of whipped cream. So light footed and agile. The Susvara seemed almost clumsy in comparison, which isnt to say that it is, but the 009S are very very quick. On the other hand, the Susvara, w great power on reserve courtesy of the 845, highlighted just how much information was lacking in the lower frequencies of the 009S. The Susvara had quite a bit more body, and weight in the lower and mid registers, which gave the impression of greater natural warmth. It was simply more natural, more effortless, and ultimately more pleasing to listen to at length. Some may see this tonal mass as slightly sluggish when compared to the 009S, but I think the Susvara has it more 'right'. Still, I can totally understand why some people would prefer the 009S depending on taste, and type of music. It is very easy to marvel at the great technicalities of the Stax. The 009S sense of deft is admirable but less realistic than the Susvara imo.
I expected greater holographic soundstage from the Susvara, but found them both equally adept in their own way. I would say it depends on the the style of presentation you prefer. Comfort is excellent on both. Found them comfier than the Utopia nearby. No clear winner here, both excellent headphones.