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ASUS Xonar Essence STX Review

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PROS / It has a very high signal-to-noise ratio and excellent THD.

CONS / There is no S/PDIF input, output only.

 VERDICT / This is a great sound card for streaming audio from your PC to a home theater system.

Editor's Note: This review has been removed from our side-by-side comparison because it no longer ranks as a top 10 product. The original review is below, but check out our current top Sound Cards here.

ASUS Xonar Essence STX

ASUS has been around for a very long time and has always been known for quality computer hardware. For that reason, we are not surprised at all to see one of their sound cards atop our top ten list. The ASUS Xonar Essence STX not only looks like it has the power to enhance analog and digital audio, but it actually does a very good job in almost every area. This sound card will appeal to the audio enthusiasts who requires the most out of their hardware and knows what quality audio truly sounds like.

Audio Performance

Signal-to-noise ratio, or SNR, quantifies the amount of noise corruption you hear when listening to music or other recorded audio. It takes the level of the audio signal and measures it against that of the background noise. To help you better understand how this works, at 1:1 ratio would have no background noise reduction. SNR is generally measured in decibels (dB), and the higher the number, the less background noise you will hear. Consequently, higher SNR numbers usually mean a better overall sound quality. This is one of the biggest factors in determining a quality sound card. However, just because you have a high SNR number, doesn't mean the card is going to have amazing sound reproduction.

A standard integrated chipset on a motherboard has a SNR of around 88 dB; while this isn't horrible, it also lacks the sound quality audio lovers want. A decent sound card will have an SNR of at least 100 dB, allowing you to be able to truly hear and enjoy the sound quality difference. ASUS understands this very well, and it offers the highest SNR on the market. This sound card has an SNR of 124 dB. At this level, almost all background noise is gone, which means you only hear the music or other audio.

This Xonar sound card also has a few other niceties. The Total Harmonic Distortion (THD) is nice and low, sitting at 0.0003% for output and 0.0002% for input -- outdoing most other cards in that area. This card also boasts stellar frequency response, with a wide range of 10 Hz to 90 kHz at 192 kHz. Lastly, if you want to step up the performance even more, you can always swap out the Op-amps for better performance. However, if you’re new to the world of sound cards, we highly recommend you leave the Op-amps alone since you risk damaging your card. If you know a lot about sound cards and feel comfortable tweaking them to your standards, this card has you covered.

Sample Rate and Resolution

This sound card offers sample rates and resolutions that are right on par with the industry standard: 92 kHz at 24 bit for both analog recording and S/PDIF digital output. S/PDIF input isn't available on these sound cards. Overall, the sample rates and resolutions on the ASUS Xonar Essence STX are in the optimal range for audio enthusiasts.



I/O Ports

The set of I/O ports that the Xonar Essence STX has practically begs to be connected to a nice home theater system. Most computer audio users are very familiar with the 3.5mm ports that they use for their headphones and speaker set. One thing to keep in mind is that 3.5mm ports aren't bad, but they don't have the capabilities that other ports have. For that reason, ASUS offers an input and output RCA, an input and output 6.3mm port, and a combination coaxial and optical S/PDIF output port. An adapter (included with the card) makes this S/PDIF output port possible. The card also comes with an adaptor for anyone who needs a 3.5mm connection. The combination of ports found on this card makes it ideal for home theaters or surround sound gaming.



The Essence STX is a PCI express (PCIe) card rather than just a PCI card. Although technically a PCIe is better than a regular PCI, using this sound card will take up a PCIe slot. If you already have your PCIe slots filled up on your motherboard, you may need to make some adjustments to make room. Most motherboards have plenty of expansion slots to include any additional hardware required for optimal performance. One thing to keep in mind is that sound cards like the ASUS Xonar Essence STX require plenty of space so they do not overheat.

The processor is ASUS's own AV1000, which provides excellent 7.1 surround sound performance. The card is also designed to accommodate karaoke. The ASUS Xonar Essence STX has more karaoke functions than all the other cards we reviewed, save one or two. Aside from the karaoke features, the ASUS Xonar Essence STX has vocal effects that you can play with, including microphone echoing, and it even has shift-keying. Shift-keying allows you to adjust the frequencies in a signal; in other words, it allows you to make a specific instrument standout out or fade away. For example, you could tone down the vocals if you only want to hear the instruments in a particular song. In a sense, this would work like voice cancellation, which just cuts off the top of the signal where the vocals generally reside.

API Compliant Standards

The Xonar Essence STX has a decent set of APIs. For recording, it has the common ASIO 2.0, and for gaming, it has OpenAL, which is rapidly becoming the new standard. Aside from those, it has DirectSound and Dolby Digital Support for the rest of your ear-pleasing needs. We would like to have seen EAX and DTS, since EAX is one of the main gaming APIs and DTS is just as common as Dolby Digital when it comes to home theaters. However, even without these two APIs, we feel that the ASUS Xonar Essence STX has the necessary API-compliant standards for most audio uses.


There is always room for improvement, but the ASUS Xonar Essence STX still outweighs the rest of the competition. The high signal-to-noise ratio, low THD and overall quality design of the ASUS Xonar Essence STX gives it a huge head start in the world of sound cards. If you want a card that is customizable and includes the necessary I/O ports for surround sound system or hardcore gaming, you will find this one offers just about everything.

ASUS Xonar Essence STX