I had some time to listen to the Tobby. Just initial impressions so things may change, but I'm impressed so far. I think it is fair to say that this is pretty neutral, though I don't know if I would go as far as saying it is "analytical" because those have a lot of negative connotations that go along with it. Yes, the Tobby leans towards a more neutral and detailed sound, but is definitely not clinical.
There is a great sense of space and airiness that I was looking for in a DAC and that I felt the D100 I had before wasn't able to completely deliver. The D100 was a great unit and definitely an awesome value, but the sound was a bit too forward for my liking at times. The Tobby manages to be detailed and spacious without coming off as clinical; I did not detect any sibilance and the sound maintains a smooth natural character. I was afraid that there wouldn't be enough bass, but listening to some contemporary tracks quickly confirmed that my fears were unfounded. There isn't any coloration, but if the original recording calls for bass, you won't be disappointed.
This is kind of splitting hairs and more of an issue of personal preference, but if I had to pick at something I might bring up the mids. I kind of have a soft spot for forward and liquid mids (e.g. the RE262) and the Tobby doesn't deliver this. To be honest, this is probably a good thing since that means there isn't any coloration, but in my personal preference I wouldn't have minded if the mids were just a tad more forward. Splitting hairs, yes, but I'll get used to it and it's probably something that I can, and should, tweak with tube rolling.
If you're part of the camp that believes a DAC shouldn't color the sound then you should probably give the Tobby a good hard look.
The cherry on top would be if Firestone could somehow implement DSD through a future firmware update since the XMOS USB input should be capable (oh and not to mention, the USB implementation for PCM has been flawless so far).