You probably have already seen my initial impression on the D100 if you read through the excellent review thread started by project86. It's been about a month now after I posted it, and I still enjoy listening to my D100 and love it even more now.
I use the D100 with my headphones, headphone amp and computer speakers, and the source is my laptop. The DAC section is very detailed and analytical sounding which I like because it shows you exactly what the recording is like. The AMP section is quite good as well. In fact, to my ears, the difference between the build-in amp and my Glimore Lite is subtle, at least on my K701s and HF2s. The background is absolutely silent. I couldn’t hear any background noise with my K701s and HF2s not even with my IEMs.
The line out is fixed, so the volume control only affects when using the build-in headphone amp. This is not a problem to me now since my computer speakers (AV40s) have a volume control. Although I do not plan to build a balanced rig using the D100, the XLR balanced outputs will still come in handy when I upgrade my speakers to some Bx5a monitors which have XLR inputs. However, in this case, it would be better if the D100 had preamp outputs since the volume control of the Bx5a is at the back. That being said, to solve this problem, you can simply add a pre-ampilfier between the D100 and your speakers/monitors.
Lastly, the USB input is actually quite good. I am not sure if it is because of the Asynchronous USB mode (versus Adaptive USB mode) or has anything to do with the ASRC process, but it is very close to the coax input.
To conclude, the D100 represents incredible value for less than $500 shipped. It is an excellent DAC with many input (AES, USB, Opt and Coax) and output (fixed line out and balanced out) options, and its build-in amp is not far behind too and offers a lot of value if you are looking for a dac/amp combo.
Pros - Many I/O,similar DAC/USB partsto Benchmark DAC1,adjust for HP out to HP character, power switch (really), relatively neutral mids oriented sound
Cons - Fake sound-stage feel on the highs (bit like K702 on any amp), my unit initially may have had problems or was it burn-in.Power-on click on HP.
Read the pros and cons, otherwise: Very nice DAC with similar features to DAC1 + screen, power switch and HP mode switch. Possibly higher noise characteristics because of that.
Input jitter elimination possibly as good as DAC1.
In the box
Manual, power/usb cable - pretty standard.
No complaints for the case box, never opened the unit though.
I thought Benchmark DAC was highs-centric and mids being somewhat recessed. D100 is mids centric to me. Good details on mids and highs, nice bass. A bit of a fake soundstage feel (if you heard K702 compared to other headphones, then you'll know what I mean). I think people often mistake treble amount for detail and resolution. Well, DAC1 was treble-focused(the treble was not rolled off enough for my liking and that give me the impression that the mids were not detailed enough and/or recessed) (see my review for it). Yulong D100 was close to just right for me. (both on line out and HP out).
Lots of I/O, sound mode to potentially tame bright headphones (pity it does not extend to line out, some people would've found that useful)
USB does 96k/24b without drivers. Having had poor experience with Musiland's buggy custom drivers, this probably is a good idea. However, 96k/24b is not uncommon or particularly impressive nowadays. Still, the 'sweetspot argument' and ASRC to 110khz make this a moot point (see below)
The DAC1 manual talks about the jitter immunity thing and de-emphasis filter. Neither really seem to be unique to DAC1. Have a look at the datasheets below. Most DAC chips to de-emphasis. Now for the jitter immunity part: The Yulong D100 DAC section (well, the USB path) is nearly the same as DAC1 (pretty sure someone said it's the same as the m902 or Stello (can't remember,but can't be bothered googling at the moment - spent too long cooking). In any case, according to the DAC1 manual, it seems like most of the anti-jitter benefits on the DAC1 come from the USB->I2S->AD1896(mostly here actualy) ASRCto110k->AD1853.
So it looks like D100 will do well there too, since it goes USB->IS via TSA1020B->AD1896 ASRC to 110k->AD1955 (pretty similar to DAC1 there, except the newer AD1955, that seems to have marginally better THD+N, and SNR and a whole heap of circuits relating to things we don't need (DSD, etc))
I'm a bit confused about the 24b/192k stickers on both DAC1 and D100. I really thought that internally it'll all be ASCRed to 110k regardless of the input SR and input type. Even if your input is 192k via, say coax. The D100 review/benchmark do mention that is the case/110k max is for both the stability (AD1896, not AD1955 as the first page says as per http://www.benchmarkmedia.com/discuss/feedback/newsletter/2010/07/1/asynchronous-upsampling-110-khz ?) and DAC section performance sweet-spot being 96khz. I certainly believe them about the sweet spot being 96k
Presuming it's (fft 1k 0db for 48,96,192k sr) they (benchmark media) look to be correct.
So, provided my unit is not faulty with me finding it mids-centric and not neutral (compared to DAC1), it's a valid value for money alternative or side-step from DAC1. The only thing you probably won't feel: the hp amp is probably not a 0-feedback one. THD+N is probably higher on D100, (re: BnB opamps, screen, etc)
RECAP after about 6 mths of use
Well, I had several problems:
-the vol knob came off since it's made of cheap plastic and not a metal one held by a screw
-the unit died, possibly overheated, now all outputs have some sort of static, distortion and humming/buzzing.
-the unit refuses to accept input after I either connected or switched on an external amp (just says 'noinput' and doesn't accept the signal via usb).
-loud clicks in the HP when you switch the unit on/off.
In light of these (especially the breaking part), I've revised the review scores and lowered quality and design to 1.5 and 3 respectively. I hope Audiophile china and/or Mr YuLong help me out and fix it. (getting a replacement unit next week (21st Mar))
edit: got a replacement unit, took about a month. Probably won't be keeping it.
Pros - Price is nice, very transparent DAC, headphone amp is pretty high caliber as well, lots of features, great build quality
Cons - analog inputs would be nice
Skylab already linked to my review, so I'll just summarize here:
I find the Yulong amp to be very neutral and transparent sounding. I've owned various models in the $1,000+ range including Benchmark DAC1, Grace Design M902, and Lavry DA10. This Yulong competes well with those units and is even superior to some of them in certain aspects. The headphone amp, while not quite on the level of the DAC section, is still quite good, and you'd need to spend a significant amount of money on a standalone amp to get much improvement.
Bottom line: if you are in the market for a DAC on the level of Benchmark/Lavry/Grace, and are willing to sacrifice some brand name prestige, you can save a lot of money by going with the Yulong.