Wednesday, 7 November 2012

Kingrex UD384 USB DAC and U Power

A long awaited review but I had to take more time on this unit due to its dual functionality.

When I was first contacted by Kingrex via email, I thought it was a friend of mine playing a prank on me. But when I looked at their website, I decided to reply their email and 3 weeks later, I received the UD384 USB DAC and its matching U Power battery based PSU.

So what is this UD 384? Its actually a 2 in 1 USB DAC and SPDIF convertor. The latter is meant for those with DAC that does not have a USB input. Similar function to Musical Fidelity V-Link and M2Tech SPDIF convertor.

The U Power is basically a PSU which comes with a built in rechargeable battery. It is claimed that it will then supply a more stable power to the UD384 DAC compared to the plug that came with the UD 384 DAC.


Both unit are of the same size, makes it a good match. Its lightweight it fits easily in the palm. Given the size, it is actually quite a sturdy unit. I believe some basic engineering design was put in for the casing as it has sufficient weight plus 4 small rubber 'pads' installed underneath the units; to withstand movement when you placed it on the table. Even with my stiff Cambridge Audio interconnect, the unit did not move when I connect it to my set up/Bose speakers. The casing is made of aluminum with black hairbrush polish.

The 2 units can be stacked together making it look like a matching pair. It measures 88 x 82 x 24 mm.

The UD384 comes with a 3 pins UK ‘walmart’ power supply, A-B USB Cable and a thumbdrive which has the required driver for Windows, plus some music samples (well at least for the unit I received). Readers may be familiar with my particular dislike against those 7.5V power supply plugs but thats just me. The yellow power indicator LED is also very soft to the eyes.

The U Power comes with the same 3 pin UK power supply to recharge the battery, another power supply cable to connect from U Power to the UD 384 and a product manual. It has a switch to choose between supplying power to the UD 384 DAC or to recharge the battery. The green power indicator LED is also very soft to the eyes.


UD 384:

Input: 1 x Asynchronous USB B input

Outputs: 1 x pair of gold plated stereo RCA, 1 x SPDIF coaxial

U Power:

Input: NIL

Output: NIL (just 7.5 V out to the UD384 DAC)


The UD384 can direct stream from PC or Mac at 16 bit/44.1KHz to 32 bit/384KHz through analog output –RCA & digital S/PDIF output. The UD384 is running in asynchronous mode for best performance. The master clock generator is a classy 1ppm TXCO unit with proprietary low-jitter drivers for Windows & Mac. Direct Sound, ASIO4ALL, and WASAPI are all supported and run smoothly.

For the RCA output, it can handle sampling rates of 44.1 KHz, 48 KHz, 88.2 KHz, 96 KHz, 176.4 KHz, 192 KHz, 352.8Khz and 384Khz and bit rates of 16, 24 and 32.

Unfortunately, for the SPDIF output, it can only handle sampling rates of 44.1 KHz, 48 KHz, 88.2 KHz, 96 KHz, 176.4 KHz and 192 KHz and bit rates of 16 and 24 bit 2 Channel. For this particular section, I can confirm that as I connected the SPDIF output to my Musical Fidelity M1 DAC which can show the input signal.

Both of the outputs here can be used simultaneously. So, you can connect to a headphone amp and a DAC simultaneously, for example.

Setting Up
Connecting to my Mac and Macbook Pro was easy. Basically plug and play. No driver installation required (that’s why I am keen on Apple products!). Connect the UD384 via the supplied A-B USB cable and the Mac recognizes it and chooses this output automatically. No issues encountered using both iTunes/Bitperfect and also MPlayerX (for FLAC) on this unit.

Connecting to my Window Vista based Dell laptop was not quite straight forward. As opposed to my Naked USB DAC….., the UD 384 cannot be connected via my laptop docking station. My laptop just cannot detect the unit. Installation of the provided driver also could not be completed with an error message stating that there was a component missing. Kingrex have been informed of this issue. However, being an IT dummy, I just tried connecting the USB cable directly into my laptop instead of the docking station, and Voila, it detected the UD 384. Then the excitement started.

Another issue is that, as my laptop is about 10 ft away from my hifi set up, I had to use a long A-B USB cable (about 3 m in length). This is my usual set up when I connect my laptop to MF M1 DAC. However, using a long USB cable with the UD 384, it created a loud continuous clicking sound through my hifi set up via the SPDIF. Hence, for this review, I had to set up my laptop near enough to my hifi set up.

There are some settings need to be changed on the laptop sound output which are clearly explained in the UD 384 manual with a snapshot of the laptop instruction step by step.

Review Set Up

1. For the office use:

a. Hardware: Window Vista Dell laptop

b. Software: Window Media player for FLAC, iTunes for 320 kbps/48 kHz MP3s and WAV files

c. Speakers: Bose Companion II

d. Interconnect (UD 384 RCA to Bose speakers): Cambridge Audio 700 Series

e. Comparison: UD100 DIY ‘Naked’ DAC

2. For home use:

a. Hardware: Macbook Pro

b. Software: iTunes for 320 kbps/48 kHz MP3s and WAV files, MPlayerX for FLAC

c. Amplifier: Musical Fidelity M6i + M1 PWR power amp

d. Interconnect (UD 384 RCA to M6i amp): Cambridge Audio 700 Series

e. Interconnect (UD 384 SPDIF to M1 DAC): Cambridge Audio 500 Series Coaxial

f. Comparison: Musical Fidelity M1 CLiC streaming from WD NAS

g. Siltech Classic Anniversary 330L speaker cable
3. For both set ups, I opted to use the U Power to run the UD 384. Hence, I am not reviewing the benefits of using U Power as oppose to plugging the UD 384 to a wall plug.

The Test Tracks

1. Siboh Kitak Nangis – Zee Avi (MP3 320 kbps/48 kHz)

2. My Hero – Foo Fighters (MP3 320 kbps/48 kHz)

3. Hotel California – The Eagles (24 bit/192 kHz FLAC)

4. Enter Sandman – Metallica (24 bit/96 kHz FLAC)

5. Time To Say Goodbye (Live in NY) – Andrea Bocelli (24 bit/48 kHz FLAC)

6. Kingrex supplied tracks with various bits and sampling rates up to 384 kHz

The Office Session

The first time I connected the UD 384, I played Siboh Kitak Nangis by Zee Avi because this was the track that mesmerized me when I reviewed the Naked DIY USB DAC. Straight out of the box, the UD 384 sounded a bit harsh but the sound staging was really evident. Direct A/B comparison (by switching the sound output between UD384 and naked DAC), the UD 384 excel with sound staging. With the track already gave me an emotional experience during the Naked DAC review a few months back, I experienced the same emotional session but with more liveliness and involvement to the music. The vocal was much upfront and the music created a backdrop that made me able to visualize how the song was recorded in the studio. It was indeed a step up to the Naked DAC. But it does cost about 18 times more than the Naked DAC so its not really a fair comparison!

Playing My Hero by the Foo Fighters also gave me a similar experience in sound staging. Its almost made me think that I was listening to a live recording rather than a studio recording. The overall music sounded uplifted with a airy atmosphere. Nevertheless, the thumping of the overlapped drumming by Taylow Hawkins is still heart-pounding and Grohl’s guitar riffs are rocking as ever.

Changing to FLAC files, especially Hotel California and Time to Say Goodbye, the UD384 provided accuracy, boldness and almost balanced presentation between the highs and the lows. The vocals from Andrea was with full emotion and it can be translated into what I call a true satisfying and uplifting atmosphere in my office. However, there was still some harshness in the highs.

The harshness was so evident. The Naked DAC might have lost in the sound staging but still win with overall presentation. Hence, since Kingrex is giving me ample time to review this item, I decided to take up on the suggestion by the manual that this unit needs 200 hrs of running in. So, before I moved on to connect this item to my home hifi set up, I let it run for 200 hours in my office.

The Home Session

I first loaded all the above tracks onto both my Macbook Pro and WD NAS to do a direct A-B comparison between different DACs to process the tracks. Technically, with the above mentioned set up, I am doing comparison between 3 DACs:

1. UD 384 itself

2. MF M1 DAC where the UD384 SPDIF convertor feeds the signal to M1 DAC

3. DAC in the MF CLiC

However, for sake of simplicity, the SQ comparison is only done against the CLiC. The M1 DAC is just to confirm the functionality of the UD 384 ie: can it feed the raw and unprocessed hi res files to the DAC?

So, firstly for this, I have used all the tracks supplied by Kingrex which ranges from 44, 48, 96, 192 and 384 kHz sampling rates and played it on my Macbook Pro, feeding it to the M1 DAC. And I can confirm that the UD384 can feed raw and unprocessed signal to an external DAC. AS you can see from the picture below, the M1 DAC shows the incoming signal sampling rate. However, for I could not test the 384kHz files as the M1 DAC can only receive maximum 192 kHz. Therefore, this unit is very useful for people whom wants to get into CAS but does not have a DAC with a USB input, if one still prefers to use their existing DAC.

Now that the technical part is done, its music time. First up was Zee Avi’s Siboh Kitak Nangis. The UD384 delivers an astonishing clarity and soundstaging after 200 hours of burning in. I just cant believe that this small unit can produce such a big sound. The boldness of the ukulele strum was very evident and just blends in with her voice at a different level compared to using this unit with my office Bose speakers. The natural sound of her voice was represented by a clean and transparent soundstaging. It was indeed a very satisfying experience.

I skipped My Hero and went straight to FLAC with Metallica. Now this is where it became a very different experience. The drums and guitar riffs became very digital sounding in which it became virtual sounding It may be the quality of the file itself but playing the same file through the CLiC, it sounded more natural and bold with drums sounds very convincing and makes me feel involve and just jump on my drums to play along.

Andrea Bocelli’s track was of course the ultimate challenge for me. And the UD384 delivered what I say would be a close match with the CLiC. The UD 384 provided me with the sound staging of a live performance but somehow lacking in the tonal balance. The usual balanced highs and lows that I get from this track is somehow lacking. But nevertheless, it is actually close enough with just a few moments of the track that the UD384 looses out a bit.

The Verdict

The UD384 (and the U Power for that fact) is a next generation, no nonsense upgrade for any CAS enthusiast that can splurge more than my Naked UD100 USB DAC. It is also a unit that can provide a 2 in 1 function plus it can easily match a sub RM2000/GBP400 full deck DAC. And it excels in delivering a soundstaging that can really make you feel involve with the music. I do recommend this for people who are into hi res music because that is where you can rip the full benefit from this unit. Retails at GBP 365/Euro 399, it is a little bit on the pricey side as it can only offer one input which is the USB. And with the limited source of 384 kHz music, one can get a full deck with multiple input for the same price. But as I mentioned, if you are really serious in hi res, you will reap the sonic benefit of this unit.

For the Malaysia market, the nearest point to get a hold of this unit is in Singapore. However, Kingrex welcomes if you would like to contact them directly.

Carol Tseng

Overseas Sales Representative
KingRex Technology Co., LTD
ADD:13F-3, NO. 136