KingRex UD 384 DAC, U-Power DC Battery Power Supply, and U-Craft USB Cable Review

Computing the Pros and Cons

The U-Power battery back uses a 2600mah Lithium Ion battery. When the battery runs out you have to connect up a different USB cable and run the UD384 by itself. You can’t charge the battery while using it, so be sure to keep the battery charged. There is an indicator light on the front to tell you that you’re running out of power. I got around 8 hours on the first charge and around 10 hours on follow-up charges. So, if you listen a lot, treat the device as you would treat a smart phone and charge it often. KingRex expects a minimum of 200 charges for the life of the battery, and it can’t be swapped out.

I suppose you could buy two U-Power battery packs, just as you might buy an extra battery for you smart phone/cameras; however, I would have preferred it if KingRex offered a removable battery as it seems to me 2600mah batteries are fairly common affairs.

Compared with my Line Magnetic CD215, the KingRex was out of its element. The CD 215 is a very good $1,500 tube CD player out of China, and has more body and a greater sense of the hall as did the Audio Note CD 2.1x MkII I reviewed awhile back. This is no knock on the KingRex because the Line Magnetic CD player is one of the best sanely priced CD players around and it’s three times the price of the KingRex, while the Audio Note player is about six times the price.
I don’t want to delve too much into the array of music I used for this review, but I want to note that I used a variety of music and a variety of recorded bitrates — mostly in FLAC but some in WMA Lossless — and found no glitches outside of the one I mentioned about the add-on USB HUB. I have listed below the main albums I used, an noted the bitrate if higher than CD quality 16/44.1.

I think KingRex has made a very solid entry into the budget realm of computer audio players that unlike some competitors is also very portable and straightforward in aesthetics and operation.

Albums used in this Review (higher resolution noted otherwise these were 16/44.1 FLAC or WMA Lossless)
Acoustic Alchemy: Against the Grain / Louis Armstrong: What a Wonderful World (24/192) / Eva Cassidy: The Best of Eva Cassidy / Daftpunk: Random Access Memories / Daughter: The Wild Youth / Miles Davis: Kind of Blue (24/96) / Florence and the Machine: Lungs (24/96) / Hailstorm: The Strange Case of… (24/96) / Allison Kraus & Union Station: Paper Airplane (24/96) / Lady Gaga: The Fame Monster PT .1 / The Magic of the Oboe (Erato Label)/ Loreena McKennitt: Parallel Dreams and The Muse / Sophie Milman: Take Love Easy/Wes Montgomery: Impressions / The Outfield: Play Deep / Antonio Vivaldi Concertos (Sony SK62719)/ The Yellowjackets: Collection

Comment from Carol Tseng of KingRex:

Dagogo and Richard Austen,

Thank you for the Review. There are no factual errors, but it would be better if you could mention the pros and cons of using the 2600mah battery. The philosophy of U-Power is a totally clean battery power supply, as the input and output are two independent circuits that sustain the clean power supply, and we think there might be distortions if we allow the battery to charge while being used.

With the Best Regards,

Carol Tseng
KingRex Technology Co., LTD