Yulong U100

General Information

Compact USB DAC/amp

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Pros: Amazing value for money. Big step up from PC onboard sound. "Feels" like quality - nice stepped metal volume control.
Cons: "Yulong" sticker instead of etching on front panel. Not the prettiest piece of equipment.
This was my first step in trying to get decent sound out of a PC (playing MP3 files via WMP).
With xFire GPU's there wasn't much room for an internal sound card, and I wanted a volume control I could use easily regardless of the application I was in.
These came up on massdrop, and after reading a few reviews I figured there was nothing much to loose.
It arrived the same day as my Philips Fidelio L1 Audiophile Headphones
I was bitterly disappointed with the headphones (sold them soon after) - but the little DAC / amp took my AT-700's to a whole new level, and 18 months later I still use it daily and still enjoy the sound.
This is a pretty simple bit of gear. Line in, USB in and L / R RCA out, along with a power socket populate the rear.
On the front a simple on / off push button with red LED power indicator, a 1/4" socket, and that lovely stepped volume knob.
The front plate attaches to the chassis with 4 x alan bolts.
My only gripe (and it's nit-picking, esp. at this price point) is the Yulong branding is on a (gold) sticker, instead of etched in black like the other printing on the front of the unit.
While I'm being picky about cosmetics, the top and bottom of the case meet in the middle along the sides, leaving a seam. To be honest though I never really noticed this until today as the unit sits on a shelf on my desk, under the desktop so only the front is really visible.
Mine is connected via USB, and was pretty much "plug and play" with W7 and W10. I only had to go into the PC settings and tell it to use the Yulong audio device for output.
Some people gripe about the stepped volume being hard to get fine adjustments.
That may be so with some headphones, but with low impedence (32ohm) headphones it is WAY louder than can be used, so I have windows volume set to 25, which effectively reduces each stepping to 1/4 of what it is at %100 volume. This still drives my headphones to over 90bD.
When I first heard the sound from this little amp I was blown away at how good it was (listening with AT-700's). It was warmer and fuller and more detailed than the PC onboard I was used to.
I replaced the 700's with a set of 900x's, and they were even better (although nowhere near the improvement I'd found by adding the Yulong). Along the way I learned about FLAC files, so I re-ripped all my CD's (and bought a bunch of new ones).
Now I'm using some Fostex TH-X00's, and they also pair well with this cheap little amp. I'm hearing even more detail, and the mellow yet emphasised bass is audio ecstasy to my ears.
After almost years I'm now looking at upgrading my DAC/amp, something like a Schiit 2 Uber stack or the MD Grace m9XX, and keeping the Yulong for work, or passing it on to someone else in the family. I'm hoping the upgrade will be worth it, as the cheaper option will be almost 4 x the cost of this unit, and the Grace 5 x the purchase price.  
In summary - if you are considering an inexpensive DAC / amp to try and you can find one of these for a similar price, grab it. You won't be disapppointed.
Pros: Powerful, transparent, RCA outputs, Line-in for Independent Amplifier use
Cons: Plastic volume control, stepping a little fiddly for sensitive headphones
I wrote this review for my blog yesterday and wanted to post it here to shout about this really great device.
Yulong makes three models of DAC. Their flagship model (D18 Sabre) seems stunning but its difficult to compare to other models that I've reviewed because it's not exactly the most elegant solution for desktop headphones. Not only is the Sabre DAC sporting beast a lot more expensive but it's not combined with an internal headphone amplifier and perhaps more crucially has no USB input. For all of these reasons most desktop users will want to stick to likes of the U100 or D100 mkII.

The U100 costs £172 and uses the Cirrus Logic CS4398 DAC chip. The chassis may not be small but it feels very much like a cut down version of Yulong's mid-range D100 mkII. Both are mains powered, desktop USB DACs with built in headphone amplifiers. At about half the cost of the D100 mkII the U100 understandably shaves some features off it's bigger brother's specification. Gone are things like S/PDIF and coax digital inputs, balanced XLR outputs, a backlit display, asynchronous USB and a high gain headphone output. The U100 might be a more basic device but it does have one trick that the D100 mkII does not and that's the ability to use it's amplifier independently (via the line input - on the back).

The U100 delivers a fast, clean and very neutral sound that impresses hugely for it's price. It's strongest points are an abundance of detail and a wonderfully expansive soundstage. It makes for a very airy sound with a healthy dose of authority and instrument definition is beautifully layered. 
The mains power seems to have a great effect on sound quality. I have never heard a USB powered DAC/amp that can touch this sound, but as well as quality you of course get an abundance of quantity. The headroom in the volume department is impressive, even with the 600ohm Beyerdynamic DT880 I found loud levels at less than 50%. Clearly a gain switch is not needed here.

Previously I've avoided talking about specific music tracks in the DAC and amplifier reviews. I was worried that it would get confusing, but I'm going back on this as I feel it will better describe certain sound characteristics.  

  1. Megadeth: "Train of Consequence" - This track feels superbly three dimensional from the very first sound. With an edge to the guitars and wonderfully clean vocals it sounds great but the thing that beats most USB powered DACs here is the faster and more airy presentation it brings. Warmer headphones from Denon, VModa and Audio Technica can often feel dull with metal like this but the Yulong's DAC/amp combo really makes them shine regardless.
  2. Skrillex: "Bangarang - feat. Sirah" - I was a little concerned there would be a lack of warmth in the Yulong for electronic / dubstep but the clarity and pace wins me over again here for a more enjoyable sound. It's not like the U100 tones down the bass slam, you just feel more like it's been left up to the music and the headphones. 
  3. Filter: "It's Gonna Kill Me" - This is a delicate mix of quiet patches broken up by bursts of moderate agression. It's not an overly forward track, nor does it have the best mastering, but its a great song and the Yulong shows it up to be exactly that.  It hides none of the inconsistencies, but a transparent presentation is always a good thing in my opinion.
  4. Dvorak:  "Cello Concertos & Orchestra No. 2 in B mino, Op. 104" - Like most classical pieces the volume is a bit low but crank it up a bit and you're rewarded with a fantastic mix of sounds and power. This is a great test for soundstage if your headphones, DAC and amplifier are up to the task. Rest assured that the last two are covered with the U100. 
  5. Jerry Goldsmith: Rambo: First Blood "Escape Route" - This is a rather quiet passage, lots of subtle instruments which set the tone for the movie and they are presented with great delicacy through the U100. The crescendo, with it's heavy strings, make me wish I wasn't combining the U100 with rather bass-lite headphones right now... OK I just switched them it shows that the issue was not with the Yulong.
  6. Duane Eddy: "Scarlet Ribbons" - The version of this track that I have has rather a lot of background noise, there isn't much the Yulong can do about that, but the guitar sounds great. When the bass guitar kicks in it really shows that there isn't anything lacking in the low frequencies and the control of that bass sounds great.

I chose these songs because they're on Spotify, so if you have a premium subscription too you should be able to find them easily and check them out in 320kbps compression. I own most of these on CD so I also tested them as lossless files through JRiver (MC17), using WASAPI - event style buffering off the RAM for the maximum possible quality.

If you already own a USB DAC/amp under £100 (like a Fiio) and are looking to spend a bit more money to make your sound even more exciting then the U100 offers a great upgrade path. The U100 will give you a more neutral, better texture in the detailed and a more three dimensional soundstage. 
The U100 even makes great performing gear like Audinst's HUD-MX1 sound rather flat and lacking in excitement whilst not adding too much to the cost, but how does it compare to things more closely matched in price?...

The Epiphany Acoustics EHP-O2D is priced pretty closely to the Yulong U100 and their features are similar. Both chassis' are simple, but sturdy metal boxes that house a good quality DAC. Both require mains power, include line inputs for using the internal amplifier independently and have nice analogue volume controls. The Yulong is quite a bit bigger, but uses that hefty back panel to add RCA line outputs as well, making it a more enticing option if your desktop computer also has speakers. I am similarly impressed by these two devices through headphones, both have great detail, clarity and soundstage.
The Epiphany has a nice smoothness to it's presentation, but it's squarely on the warm side. This produces a wonderfully plump bass without affecting detail in a huge way. The U100 on the other hand displays almost none of that colouration, it sounds fast and neutral. That's not to say that it completely lacks bass (unlike the CEntrance DACport), it just doesn't emphasise it and the detail comes through more clearly because of this. 
The Yulong's chassis is better for a neat desktop as the power lead attaches at the back. The U100 has more volume on tap for high impedance headphones, even with the Epiphany's gain switch on (which I would not recommend), but the Epiphany's volume control is much nicer as it doesn't have stepping and is really smooth. These two machines are closely matched overall so choosing between them should be carefully considered and probably based more on presentation than anything else.

The Arcam rPAC is also a similarly priced DAC/headphone amp combo with RCA outputs but there the external similarities end. The rPAC is considerably smaller, doesn't have the larger headphone socket, runs from USB power and has no analogue volume control. It is however almost up to the standard of the Yulong U100 but with a slightly warmer signature, closer to the U100 than the Epiphany Acoustics EHP-O2D though so it could be a nice balance for some people. The rPAC's sound suffers a little from the USB power, but it makes up for this with considerable convenience as you can take this anywhere with a laptop and enjoy very high quality audio and with less cables too.

I can't really finish the comparisons section without talking a little bit about the U100's bigger brother - the Yulong D100 mkII. This DAC is nearly twice the price of the U100 and for that you get a lot more inputs / outputs, a screen, a dedicated headphone socket for high gain setting, an option to roll off the treble (very slight) and it supports up tp 24bit 192khz audio. 
Sound wise the D100 mkII also makes improvements across the board. Overall it displays a greater presence, a more dynamic soundstage, better control in the upper frequencies and an even better resolution of detail. The bass is a touch more plump, but not by much and Yulong have been careful not to make this effect low frequency texture or creep into the mid-range. The music feels more endowed with a sense of authority and power with the D100 mkII that make it very hard to beat anywhere near it's price.

When I first saw the U100's front panel I thought the unit was quite small because I assumed the headphone output was the more common, smaller 3.5mm (1/8") type. Thankfully we get the proper full sized 6.35mm (1/4") connection here and this means that although it's a good bit smaller than the mid-range D100 it is still firmly in the desktop sized arena (160x110x30mm / 800g).

The box is solid, easily disassembled and nicely neat for sitting on a desk. I am pleased to see the larger headphone socket here. This unit is a nice choice for headphones that only have this size connector and converting down is so much easier than up so two thumbs up from me here. The volume dial is nice, well underneath it is anyway, the actual bit you touch is plastic so doesn't feel that great but what really bothers me here is the stepping. I know some people will prefer this but I don't get on with stepped volume controls, even when they have a decent amount of steps like this one. How long is it before you come across that annoying '7 is too quite and 8 is too loud' scenario? This is the down side of not having any kind of gain control. with sensitive headphones, like the 25ohm Denon AH-D7000 the inability to reach the desired volume happens more often, although you can offset this issue by slightly adjusting the volume in software. With the 600ohm Beyerdynamic DT880 this will never be a problem.

The Yulong U100 reminds me very much of the Epiphany Acoustics EHP-O2D in terms of overall sound quality and it's emphasis of that quality over other aspects of the design (to choose between these two models look back at the comparisons section), but they're both equally as impressive and that's no small task. 

If you are considering the U100 I will assume the mains power doesn't bother you and you don't need the convenience of portability... Well, if you can live with these aspects then congratulations because this elevates the audio quality well beyond the similarly priced USB powered competition. 

Choosing between the U100 and it's bigger brother is possibly an easier choice as it can be settled purely by how much you are willing to spend and/or what connections you need. If you can't stretch your budget to the D100 mkII then the U100 makes a fantastic budget option with a healthy taste of that same stunning sound quality - watch this space for a full review on the D100 mkII soon.

Here is a shot of the U100 with it's bigger brother - the D100 mkII, with the Audinst HUD-Mini and Fiio E17 sat on top. Hopefully this gives a better understanding of scale. Once I have written reviews for the Arcam rPAC and Audinst HUD-Mini I will be moving on to the D100 mkII.
And finally one of back panels / connections. Comparing the Yulong U100 & D100 mkII.

How does this sound used with the dac bypassed?Using the mini in from a cd player?
Is the line input a 3.5mm audio jack? Can plug in any device that uses 3.5mm and play music through that? I would like to find a DAC that I can plug an mp3 player into (3.5mm) and connect to my stereo through RCA. Would this device work for that?
My one has an Aluminium volume Knob
Don't got the U100 anymore


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