ASUS Xonar Essence One

ASUS Xonar Essence One

The USB sound card that turns your PC into proper hi-fi equipment 

The Asus Xonar Essence One’s sturdy black metal chassis looks more like a traditional hi-fi unit than your average USB audio device, and inside you’ll find a C-Media CM6631 audio processor and a pair of Texas Instruments  Burr-Brown PCM1795 DACs. 

It has professional inputs and outputs too. The front 1/4in jack socket can drive headphones of up to 600 ohms impedance, but can also handle 16 ohm earphones without difficulty. At the back is an RCA phono output and a pair of balanced XLR outputs – the latter are ideal for using with studio monitors, as they minimise interference and can cope with long cable runs. Meanwhile, the mains power connection and asynchronous USB input are designed to eliminate interference and jitter.  

 There are also optical and coaxial S/PDIF inputs to connect external audio devices such as CD players, with support for playback frequencies of 44.1KHz, through to 96KHz and up to 192KHz. You also have the option of hardware upsampling, which interpolates frequency data to create the impression of a higher sample rate, although the improvement is very subtle. 

In addition, the Essence includes a toolkit and a box of alternative op-amps containing four Texas Instruments Burr-Brown OPA2132P and two National Semiconductor LM4562NA chips.  

The thoroughly illustrated installation instructions are reassuringly comprehensive. Separate banks of op-amps handle different elements of the sound; you’ll need matching sets for each stage. The main bank of four converts the current output by the DACs into voltage; a second pair acts as a low-pass filter to eliminate background noise, while each output (headphone, XLR and RCA phono) has either one or two op-amps serving as a final stage amplifier.  

There are four JRC 5532D op-amps at the first stage and two more acting as low-pass filters. The RCA output has a National Semiconductor LM4562NA op-amp, as does each of the balanced XLR outputs, while amplification for the headphone output comes from two National Semiconductor LME49720NA op-amps. It’s well worth applying the suggested  upgrade of OPA2132P and LM4562NA op-amps to the first and second stages respectively – they make for a more detailed and balanced sound.

With the default 5532D op-amps, we found the sound too bassy, with a slightly enclosed sound that detracted from the subtlety of mid-range tones. Switching to the Burr-Brown op-amps produced more detail and a clearer distinction between bass and low mid-range though. Percussion sounded precise, with clear, organic-sounding drum slaps, and the wide soundstage and accurate positioning made it sound as though we were in the room with the musicians. Music of all sorts sounded great, in fact, from crunchy guitars to the natural timbre of orchestral strings. You can get even better results, perfectly customised to your own taste, if you upgrade with carefully selected third-party op-amps too.
 

CONCLUSION 

The Essence One bridges the gap between hi-fi DAC units and USB sound cards. Its sound quality is among the best you’ll hear from a PC, making it perfect for anyone who has moved their music collection to their computer. However, gaming and movie fans should note that it lacks support for digital, analogue or even virtual surround sound. There are also no analogue inputs for recording or chat.  

You pay a premium for this quality, though, and you’ll need good equipment to get the most out of it. There’s no point in spending £300 on a DAC if you’re going to connect it to £20 speakers and the earphones that came with your phone. If you can afford the proper setup, though, PC audio doesn’t get much better.
 

HOW MUCH? Price £330 inc VAT  

 

IN DETAIL 

Processor C-Media CM6631 

Interface USB Maximum channels 2 

Maximum sample rate 24-bit/192KHz 

DACs 2 x 24-bit Texas Instruments Burr-Brown PCM1795 

ADCs None 

Inputs USB, optical/coaxial S/PDIF inputs 

Outputs 2 x XLR, stereo RCA phono, 1/4in stereo TRS 

Audio technologies Hardware upsampling 

Extras Op-amp upgrade kit
 

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