ASUS today announced the Xonar Essence STU USB external digital-to-analog converter (DAC) and headphone amplifier, based on the acclaimed design and quality of Xonar Essence ST/STX internal sound cards and going beyond their already high standards. Offering audiophile-grade performance, Xonar Essence STU delivers USB connectivity and accessible external controls. It offers clear sound with a 120dB signal to noise ratio (SNR), strong 600ohm headphone amplifier, asynchronous USB audio and swappable Op-Amps for DIY sound modification. Precision clock tuning technology further enhances audio fidelity, making Xonar Essence STU a great choice for discerning music lovers who need a quality DAC and headphone amplifier to drive the full capabilities of high-end headphones. "We received considerable positive feedback from customers regarding the excellent sound quality of Xonar Essence ST/STX sound cards, which led us to develop Xonar Essence STU as a USB device that offers even more premium audio quality plus easy controls and connectivity to notebooks. This is another example of ASUS listening to the community and acting on consumer demand", said Ives Chiu, Audiovisual Product Manager at the ASUS Multimedia Business Unit. High quality precision audio Xonar Essence STU delivers clean, clear, and low distortion sound with 120dB SNR. It achieves this thanks to exacting hardware design, which includes balanced (or mirrored) PCB layout for accurate reproduction of all sound sources and minimal component crosstalk, or interference. ASUS uses audio industry-leading components such as the Texas Instruments PCM1792A DAC and TPA6120A2 headphone amplifier, which supports up to 600ohm impedance. Also included are audiophile-approved WIMA FKP2 and Nichicon Finegold capacitors for balanced and rich sound. To satisfy the most demanding users, Xonar Essence STU features precision clock tuning technology and asynchronous audio transfer. Both ensure accurate and jitter-free sound fidelity, allowing customers to enjoy music in its purest form. Bit-perfect playback is aided by support for ASIO audio drivers. Complete ease of use As an external device, Xonar Essence STU offers readily-accessible controls with no need to go into software menus. Customers can switch between low and high gain settings, accommodating better listening experiences across a wide range of headphones, from in-ear headsets (typically 16ohm-32ohm) to premium full-size headphones (up to 600ohm). This is especially useful with the increasing popularity of mobile devices, which normally ship with low impedance/high sensitivity headsets. Dual volume controls help users change speaker and headphone sound levels simultaneously, similar to features offered by dedicated audio decks. The USB interface means connectivity with USB-compliant devices, while I/O ports include stereo RCA out, a 6.3mm headphone jack, two digital inputs, and auxiliary in. Xonar Essence STU can be placed horizontally and vertically with a bundled stand, giving customers more space-saving flexibility for different locations and situations. Tonal tuning and advanced controls Texas Instruments NS-LME49720 and NS-LM4562NA Op-Amps (or operational amplifiers) deliver acoustics fine-tuned by audio engineers to support livelier and more detailed spacious sound. Xonar Essence STU has room for three swappable Op-Amps, which can be replaced by users to adjust tonal performance based on personal taste. This open-ended and customizable design is inherited from previous Xonar Essence audio products, and remains true to the series' commitment to accommodating as many customer preferences as possible. Additional advanced features are a jumper switch that re-routes sound via Xonar Essence STU, allowing it to be used as a pre-amplifier in conjunction with a dedicated power amplifier. Customers can opt to adjust master volume directly on the power amplifier without having to reach Xonar Essence STU controls. Also, a selectable DC servo headphone output can be activated to minimize pop noise which may occur when powering on.