I think he meant that the TH-900 was his favourite for bass before hearing these. English is his second language so maybe don't read everything too carefully.
I can back up the soundstage comment. People always go on about soundstage and placement and how much air there is between stuff. To be honest, I never thought headphones had or could have a good soundstage, but as soon as I put on the Abyss it was the first thing I noticed. It's really quite something else.
Like you, from what I understand, most people who have heard both the Abyss and 009, say that the Abyss is the winner in terms of bass and soundstage, and the 009 is the winner in terms of the detail and mids. Some people find the 009's too bright, some find the Abyss lacking in 'detail' (by comparison). It comes down to personal preference. I have found over the years that what some people call "detail" or "clarity", I call "hurts my ears". I work in construction and maybe a certain part of my hearing has deteriorated and that makes the midrange extra harsh for me personally. At the end of the day, most people's impressions and descriptions are probably about right, but it depends on your personal taste.
Hm, maybe. It's just that he said the TH-900 was his overall favorite in the K812 thread as well.
Emphasized treble can be mistaken as detail, but even with my limited experience, I have found that real detail comes through when everything is more controlled and focused, and you notice things you never did before. For example, I recently replaced a headphone cable (brand new vs years old of the same one). The treble used to get rather sibilant with certain material. Now, there is more treble quantity, but higher quality as well. Think smooth, yet solid and soaring. Just today, I heard background vocals I didn't even know were in a song. And what I thought was a lone guitar was actually a guitar and keyboard playing the same melody! (Those are two out of countless examples to illustrate my point of the benefits of a controlled sound with real instead of artificial detail.) With (what I now know to be) the harsher distortion of the old cable, it was so much more difficult to distinguish such things.
Very true about personal taste. I plan on collecting all these headphones some day! I'm sure I would love them all for the things they excel at, though I get the feeling the Abyss would be the closest to the sound I am looking for.