The TubeDAC-11 is a killer value - it costs $130 less than the D100 MKII, and has more inputs, pre-amp functionality, and of course the tube buffer aspect. In some ways the TubeDAC and the D100 show their family lineage.
As a DAC, the TubeDAC is more forgiving, less detailed, and more dependent on source quality (which makes sense due to lack of the ASRC circuit). Sound signatures are fairly similar overall though, so there isn't a complete deviation there. Using the Tube Out on the TubeDAC will give you a warmer and smoother result, while using the solid state choices basically sounds like a junior version of the D100 MKII.
From a headphone amp standpoint they are also similar. The original D100 had a lighter, more "ethereal" feel to the headphone stage. The newly tweaked MKII sounds warmer and smoother, which again puts it in line with the TubeDAC though more refined and advanced. The D100 does have a little more power on tap - into a 32 ohm load, the D100 delivers 900mW while the TubeDAC is rated at 600mW. The differences decrease as you go up to higher impedance loads. In real world usage, I find the D100 to do a better job powering orthos. My HiFiMAN HE400 sounds acceptable on the TubeDAC but quite nice on the D100. But don't forget the tube out option for powering headphones from the TubeDAC.... which is actually quite useful for high impedance models.
In the end, both nice units and both worth looking at.
D100 MKII pairs very well with the Sabre A18. I've been using it alot - almost as much as the D18/A18 combo. While the D18 is more musical, more open, with a smoothness that would make vinyl and tube junkies really happy, the D100 MKII is more "traditional high end DAC" sounding. A little brighter, more direct, with a less diffuse soundstage, and more focus on the sparkle. It's a nice alternative to the D18 and as I said in the review, I can picture some people actually preferring it.
V200 is a good match as well - as an amp it shares many traits with the A18, so it makes sense that if one pairs well the other would too.
Edited by project86 - 5/1/12 at 12:29pm