I used to own the T1 (sold of when I was downsizing) and currently own both the TH600 (office) and TH900 (home). Personally, I don't think the TH600 pales to the T1 at all. TH600 does some things the T1 can only dream of, while the T1 beats it on some other categories. Apples to oranges, really. Then again, I've always thought the T1 was way too dry unless you drove it with a wet syrupy amp (tubes, more often than not). If you prefer the T1 to the TH600, then I don't think the TH900 will change your opinion since it does more of what the TH600 does, only in a more refined fashion.