Pros: Smooth, natural, deep punchy bass, superb sound for its price, design, lots inputs, display
Cons: Volume knob (stepped volume control), on/off switch in rear
Let me first say that this is my first Yulong product. And while I've used many Chinese products before, Yulong stands out in its own way.
The DAC section is wonderful, it just hits exactly where I want it - at least for now, considering my listening preferences (which have a tendency to change). It hits the right notes for me. Going from a warmish DAC like the Audio-gd NFB gave me more joy in the treble department when using the D100. I firmly believe in that the DAC should be as neutral and transparent as possible (colouration should only be picked in an amplifier or change of headphones) but I would rather call its sound more natural than straight up neutral. Not that's it's any less neutral, don't get me wrong on that, I just find that rather than having very crisp highs, this DAC manages a very smooth upper end while maintaining great extension. I felt that some female vocals and cymbals etc. felt a little dry coming from an Audio-gd, and somewhat crisp from an ODAC and ST(X); but with the Yulong D100 the treble especially is very smooth and natural sounding. And even though my perception of this DAC/Amp would be that the highs would make my PRO900 for example unbearable, but not so. Sibilance I don't think you can entirely get rid of unless with some EQ (and I've owned some warm equipment), but the metallic highs can be countered, and the Yulong does well in respect to this. The smooth, yet neutral signature of the DAC--feeding my V200, provided with a very nautral sound through my HD650. And regarding the bass, it is wonderful. It goes deep and hits hard with a great deal of detail.
I would say the Amp section is almost equally as good. In comparison to the V200 the differences are quite subtle. What I noticed most of all is that the amp on the D100 provided a heavier dose of bass, mayhaps less controlled; while the V200 provided a slightly more natural sound with emphasis on vocals, somewhat more organic--so to speak. Soundstage I would say is almost about the same except that the V200 give a tad little more space (this isn't saying that the D100 has a tight soundstage, connect an amplifier that does soundstage well with perhaps a pair of cans that has arier and more open soundscape, and the D100 will expand with the rest of the equipment)
The Yulong D100 is one of those products that actually impresses me. I have heard that it should compare to DACs like the Benchmark and Lavry, but since I haven't heard either of those units I cannot make a comment on that part. From what I've heard though, the Benchmark DAC1 can be a bit bright, whereas, at least to my ears, the Yulong D100 MKII is quite smooth and polite in the upper register. If you're after a DAC/Amp with a very good Amp section, hands down the D100 is the product, especially for its humble price tag. It also has a Sound option between SoundMode 1 (which should be the most neutral) and SoundMode 2 (which should be a touch warmer). During the burn in process I noticed a slight difference between the two, but so far I preferred Mode 1 even with my PRO900 on some tracks.
Build quality is quite solid, apart from the slight cap in the back upper plate which I presume is there for ventilation's sake; as well as the plasticy volume knob which turns in toggle/clicks, rather a continuous switch, which can be annoying when you want to adjust volume precisely. The input options are plenty, and that's great. The only problem one might have is using USB which supports max 96khz. I have nothing against the design itself, I like its wide dimensions, and I love the display which adjusts KHz depending on the source, but it's a shame that the on/off switch is placed on the rear rather than on the front like say on the D18 and A18. And although it stacks with its big brothers, it's a shame it doesn't share the same colour, eg entirely black or entirely grey.
Also note, that if you plan on using the amp section, I believe the best thing would be to mute the sound/volume knob on 0, and unplug/insert headphone while the amp is on. While having the headpones plugged in while powering on/off I noticed a very strange sound, possible a similar thing that occurs with some Schiit amps that affects the drivers in some way. I could be wrong on this, but ever since I noticed it I've been plugging and unplugging while the amp is powered on and muted without any issues.
Aside from all else, for $450 this is an absolutely marvelous piece of equipment, whether you'll be using it as a DAC or a DAC/Amp, though I believe its strongest area lies in the DAC section which should yield even better results with a greater amplifier.