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The UD-10.1 is a versatile interface that presents on its back panel a plethora of digital outputs - TosLink, coaxial, AES/EBU & BNC connectors. On this end you won’t feel short-changed. On the front panel sits a type B USB input, a power indicator and a 1/8" stereo mini jack  designed for headphones or as a line-level output with the provided 1/8"-to-stereo-RCA converter. Compared to the previous UD-10, the UD-10.1 claims upgraded parts such as high-quality Japanese-Korean SMD resistors and capacitors, Sanyo OS-CON, ELNA Silmic and WIMA film capacitors and an improved circuit board. It also uses a type B USB socket rather than the more common type A version used on the original UD-10.

The UD-10.1 does not work as a preamp and volume control must necessarily be provided by the computer. As the UD-10.1 is marketed to audiophiles, Trends has been aware of the power source quality and proposes an extra rechargeable battery power supply that holds four NiMH AA batteries for a few extra clams. This cheap option might be difficult to live with on a mobile basis but you have always the option to run directly on USB power. The Trends UD-10.1 runs proprietary dual power regulation circuits instead of the standard 5V USB bus power. Whether the power arrives from battery or USB bus, it gets regulated before hitting the ICs. The UD-10.1 is equipped with a Burr Brown PCM2704 IC for USB conversion sent to the many digital outputs. Following the audio path further downstream are proprietary impedance matching circuits for the 110Ω AES/EBU and 75Ω coaxial digital outputs.

The Trends Audio USB converter requires no particular drivers to work as-is on most modern PC and Macs. It should be a bit more difficult for Linux OS and especially smaller netbooks. The UD-10.1 is limited to 16-bit/44.1kHz like most current USB audio devices. Fortunately the vast majority of content available at the moment is still at 16/44.1.

More technical specs include a dynamic range and S/N ratio of 98dB; THD+N of 0.006%; linear-regulated power for all digital  and clock paths; a 4-pin high accuracy crystal clock (±10ppm); standard IEC-958 S/PDIF or AES/EBU encoding; 32/44.1/48kHz sample rates; FLAC, WMA Lossless, Apple Lossless, WAV, AIFF, PCM, MP3, AAC, Ogg Vorbis, MP2, MusePack and WMA file acceptance; 256MB RAM with 30MB hard disk space requirement for all systems; and Windows NT/2000/XP/Vista, Mac OS X 10.3, PC LinuxOS 2007, Fedora core 7, Ubuntu 7.04 platform compatibility. Dimensions are 76 x 46 x 114mm WxHxD, weight is 300g.

Used as USB DAC & headphone amp: The Trends Audio’s stylish little steel-gray aluminum enclosure found a place on my desk top without trouble, being definitely taller than the Lite but quite similar in width and depth. Connected to the USB port of the Apple iMac, it significantly upgraded the sound over the native sound card to be less compressed and thin. For the outlay, it already was great performance for those who want to listen to music directly from the PC. I used iTunes’ encoding to WAV files stored in an external 1TB hard drive via Firewire connection. At first try, I did not distinguish obvious differences over the Lite. Both sounded the same and nothing seemed to justify the higher price for the bigger version in this precise configuration. The Lite version already represented a significant improvement over the Mac’s sound card. It effectively isolated the interference from ultrasonic switching and fan motors. Paying more attention to PRaT however, I finally succeeded at differentiating between the two boxes.

The USB-10.1 has a more accurate clock and separate power supplies for digital and analogue circuits which ultimately portray tempi with better precision to become an appreciable feature with uncompressed files. As it is the case for the smaller version, the headphones output stage goes not far with low-sensitivity headphones and direct connection is suitable only for portable headphones requiring little power like the recent Nuforce UF-30 which will still perform better with a dedicated amplifier.

Used as USB DAC into dedicated headphone amplifier: The UD-10.1 is not the highest performing small USB DAC. Nevertheless, its sound suffers no particular damning weakness. It is very clear, detailed and while it could sport better density and more bass extension, certainly not at this price. Today’s various USB DACs often include headphone sockets. This feature is boosted by the widespread use of laptops as music sources. Many don’t wish to spend much on a desktop mini system, hence the DAC/headphone amplifier combo eliminates several problems: the poor performance of computer sound cards, the poor quality of  analog audio outputs on PCs and the difficult choice of aesthetic but efficient active speakers. Yet the final result often remains very disappointing. One reason is the integration of various functions and circuits inside these small boxes. Another is the difficulty of sharing a high gain preamplification device with low distortion with a D/A conversion stage in the same minimal space.