Info

a short diary of some part of my life.


uDAC

I have never really looked at NuForce offerings until the new uDAC-2 came out recently. I tried the first generation uDAC, while the sound quality is good for the money, I dislike the channel imbalance it produces on low listening volumes. The sound of the first gen uDAC is also too warm and soft for my taste.

The new uDAC-2 is a step up over the first uDAC (uDAC-1). NuForce listened to customers complaints and suggestions about the uDAC-1. They tweaked some of weaknesses found in uDAC-1. The results are quite good. Now, I have a proper headphone amp that I can use on the go, I can also use it as a USB to S/PDIF converter. I no longer own any high impedance full sized headphones as I find them not good enough at times. So the uDAC-2 is only used for IEMs and efficient headphones that do not require huge power output to drive them properly. I don’t own the most neutral IEMs or headphones, my impressions are based on my listening sessions with my Sennheiser IE8 and Grado RS1i. Those two earphones and headphones should match or exceed some of the best full sized headphones out there. There are compact enough which is good for my hunger for simplicity at home.

ESS Sabre

Let’s start with the chips used in uDAC-2. It uses ESS Sabre 9022 DAC chip. ESS Sabre DAC is one of the well known sigma-delta DAC makers. I own a Wyred 4 Sound DAC-2 which uses ESS Sabre 9018, a similar chip equipped with excellent implementation and output stages. The point is, I am satisfied with ESS Sabre as far as potential sound quality it can produce. Other than the DAC chip that is revealed by Jason Lim of NuForce, there is no other information about other chips inside the uDAC-2. If Jason did not reveal the chip, I would have not known the chip because it has NuForce markings on it instead of ESS’ markings. Before I started using the uDAC-2, I am disappointed to read that it does not support 24/88.2. I have quite a few recordings in 24/88.2, they are also my favorites. I bet it uses Tenor TE7022 as its USB receiver, the Tenor chip does not support 24/88.2.

I have a CEntrance DACport for comparison. The uDAC-2 was compared side by side, powered with the same USB ports on my MacBook Pro i7 2.66Ghz 8GB-RAM 500GB-HDD. I also compared it with my beloved R-2R DAC, Audio-gd Reference 5 DSP. I wanted to know how far this little guy can go. Oh and, about the build quality, the uDAC-2 seems very solid. My unit has a slight misalignment on the headphone jack, but that does not bother me one bit since it does not stress the PCB. Considering the low price, I can’t complain much about the chassis, it’s definitely solid. But if you compare it with some of the best audio chassis out there, it looks okay, I guess…

Design Philosophy

Before we get into the sound. I would like to mention a few interesting findings about the uDAC-2. I have several ‘toys’ that I can compare with, they are not necessarily made by the same company, in fact, they are all made by different companies. Why? To diversify and differentiate. NuForce is one funny company. They don’t measure their gears at all. Audio experts have been asking about this very issue. That’s not the only issue, the uDAC-2 is extremely sensitive to the USB power you are feeding it with. It needs to be extremely clean: free from noises, unstable power, ground loop. It needs to be isolated. CEntrance DACport on the other hand, is virtually immune to dirty USB power. It has multiple filters in that tiny chassis. It’s also isolating itself from outside interference. I think this is an interesting finding. CEntrance cares about what we should be experiencing, high end audio without the ‘necessary’ complexities. While with NuForce, this seems to be an afterthought.

As a headphone amp…

Vs. CEntrance DACport

CEntrance DACport (DACport) and NuForce uDAC-2 (uDAC-2) do not produce any hiss at normal listening levels. They are virtually hiss-free. One of the main reason why I want an external headphone amp in the first place is to get a hiss-free experience listening to my favorite musics and movies. I hate hiss. If you have OCD, DACport is quieter than uDAC-2, but the difference is not very noticeable, especially with music playing. The DACport has much more driving power, it has the juice to drive full sized headphones with ease. The uDAC-2 drives the IE8 & Grado RS1i with ease. It does drive the RS1i well but it lacks the juice to extract its full potential. I suspect, it will have problems driving more-difficult-to-drive headphones. I don’t have any plans to acquire one, uDAC-2 will do just fine with my current phones. DACport produces more expansive soundstage. Complex passages do not get lost with DACport. uDAC-2 falters at producing preciseness in complex passages. uDAC-2 is probably better for slower musics while the DACport is good for about everything. I was torn on which one to keep, I don’t want to keep both, technology keeps improving, so there is no need to keep both of them. There will be better products in the future and they are likely to be cheaper than they are now. I ended up keeping them both. It’s kind of fun finding out how a very well designed product (in this case, DACport) offers the refinements that the inferior product (uDAC-2) fails to produce.

As a USB to S/PDIF converter…

Now, this part is a lot easier to write. As usual, I used my Audio-gd Reference 5 DSP for this test as the DAC, my superb monitors, Selah Audio RC3R powered by Wyred 4 Sound STI-500 integrated amplifier.

Vs. Halide Design Bridge

Halide Design Bridge is a dedicated USB to S/PDIF converter, just like the Stello U2 from April Music. I posted a short impression of the Halide Design Bridge on my Audio-gd RE5 review. If you are too lazy to read it, the Bridge is the best USB-SPDIF converter that I have tried.
The uDAC-2 is noticeably warmer and less dynamics. The details are masked with inferior tonal balance. The sound placement is also affected, it’s not like attending live music. 😦 To sum up, there is no area that the Halide Design Bridge cannot beat the uDAC-2. Does it make the uDAC-2 sound bad? No. I don’t usually like non-neutral gears but in this case, I’ll make an exception. If you need a USB-SPDIF converter that can tone down your overly bright gears or if you prefer warmer tones in general, this is it. I’m not trying to salvage the uDAC-2 but not everyone owns the exact same gears as I own. 😉

As a standalone DAC…

NuForce uDAC-2 has a set of analog RCA output, I thought it would be good idea to give it a run, how it performs… The output level can be adjusted by using the volume knob on the face plate. Since the output level is adjustable, it can also act as a preamp. I didn’t test the uDAC-2 preamp capability as I no longer own a power amp. This product is very flexible and offers a wide range of usage possibilities.

Vs. CEntrance DACport

DACport and uDAC-2 were feeding the superb Wyred 4 Sound STI-500 integrated amplifier. The difference between them was more difficult to find than I first thought. I even think the difference was too subtle to be noticed. I ended up playing quite a few recording that push DACs to the limit and the result was just as difficult to find out. The uDAC-2 is just a bit warmer than the DACport and DACport background is a tad blacker. The soundstage, level of details, sound placements, etc… you name it, they are all very similar. I guess uDAC-2 performs better as a standalone DAC (using its RCA outputs) than a headphone amp.

Vs. Audio-gd Reference 5 DSP (Burr Brown PCM1704U-K)

Portables will never beat full size gears, this remains true with uDAC-2 Vs. RE5. The difference is not subtle at all. Everything is much more refined on the RE5. This is not a fair comparison. RE5 has overkill designs that can only be found in exotic gears while the uDAC-2 is meant to be small as it is. Let’s start from the noise floor, the uDAC-2 has higher noise floor while the RE5 has noticeably much lower noise floor. The soundstage difference is even bigger, the RE5 is able to bring you live music experience while the uDAC-2 which is still better than not having a DAC at all, cannot bring live music experience. Tonal balance on the RE5 is also far superior. There is this magical thing going on in the PCM1704U-K that makes the music flows without hesitation. The uDAC-2 is clearly inferior and it cannot keep up with full size gears, at least if compared with my RE5, it cannot keep up. For the size and money, I don’t think I can find a better product than the uDAC-2. And that’s exactly the point of why I should keep the uDAC-2 around. It’s small, it’s cheap, and it performs admirably.

Before one makes any purchasing decisions, please do compare them side by side if possible. Go to a local meet and makes friends there. There is no way I would be able to tell every single difference between one gear with another. Comparing gears side by side the ultimate way to know which one is the best. Happy Listening!

[update]

My uDAC-2 has stopped working properly. It produces crackling sound everytime I listen to high pitch female voice. I now consider it dead. It’s only been 3 years. 3 year old. And it’s dead. I think this is a great example why we all should only purchase well engineered items.

Comments

3 Comments

Post a comment
  1. Maniz #
    October 16, 2010

    Good review 🙂 I have both udac and udac-2 i love them

  2. Randy #
    March 26, 2011

    Why my udac SPDIF out can’t work under win7?

    • hrl #
      March 26, 2011

      I don’t know, I’m a Mac user. I don’t have any Windows machine.

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