Asus Xonar Essence One review

The Asus Xonar Essence One has replaceable op-amps and is aimed at hi-fi enthusiasts who like to tinker with their kit. Indeed, it looks more like a traditional hi-fi unit than your average USB audio device. Its black metal chassis is both well built and unusually large, with a footprint of 262x210mm. Its mains power connection and asynchronous USB data connection are designed to eliminate interference and jitter, and we encountered neither.

The Asus Xonar Essence One has three audio outputs, all of which work simultaneously. At the front, there’s a 6.3mm headphone jack capable of driving headphones of up to 600 ohms impedance. We were pleased to find that it’s also able to handle 16 ohm earphones without producing the high-pitched whine that affects some other high-impedance headphone outputs. On its back panel is a pair of balanced XLR outputs that are ideal for connecting to a pair of studio monitors and a stereo pair of RCA outputs.

The Xonar Essence One also has optical and coaxial S/PDIF inputs that you can use to connect high-quality CD players and other external audio devices. A button at the front lets you switch between input sources. LEDs display the frequency of your audio source, and the Xonar Essence One supports playback frequencies from standard CD-quality sample rate of 44.1kHz up to a sample rate of 192kHz, a rate commonly used in audio production. Another button triggers the Essence’s upsampling, which interpolates frequency data to create the impression of a recording made at a higher sample rate. We found that the effectiveness of this feature was dependent on the quality of the original source. Higher quality recordings benefitted the most, but the perceived improvements were typically subtle.

The Essence One comes with a pair of angle-ended electronics tweezers, needle-nosed pliers and a screwdriver, as well as a box of alternative op-amps containing four Texas Instruments Burr Brown OPA2132P and two National Semiconductor LM4562NA chips. Swapping op-amps might sound difficult, but the Xonar Essence One comes with detailed and illustrated guide to removing and installing them.

Separate banks of op-amps handle different elements of the sound, and a key requirement when switching op-amps is to ensure that you use matching sets at each stage. The main bank of four converts the current output by the DAC (digital-to-analogue converter) into voltage; a second pair acts as a low-pass filter to eliminate background noise while each output (headphone, XLR and RCA) has either one or two op-amps serving as a final stage amplifier.

The Essence One comes equipped with 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 pair of balanced XLR outputs, while amplification for the headphone output is provided by a pair of National Semiconductor LME49720NA op-amps.

You must apply a fair amount of force to remove op-amps from their sockets, but more delicacy is involved when fitting new ones. If the legs don’t line up, you may have to bend them carefully into position before placing gentle pressure on the chip to slot it into place. It’s definitely worth applying the suggested upgrade of the OPA2132P and LM4562NA op-amps to the first and second stages respectively. They make for a more detailed and well balanced sound.

Asus hasn’t provided enough extra op-amps to upgrade everything, but you can buy additional ones online for between £2 for a very basic audio-grade chip to around £30 for a JRC MUSES 01 op-amp. There are numerous websites devoted to op-amps and Asus provides a helpful list of upgrade combinations in the manual. The JRC MUSES range is specifically designed for audio use and Asus is such as fan of the op-amps that it’s going to be releasing the Essence One MUSES, which has six MUSES 01 chips at the first and second stages. The MUSES edition of the Xonar Essence One currently costs almost twice as much as the standard Essence One, so it’s definitely one for the dedicated (not to mention well-off) audio hardware enthusiast.

We compared the audio quality of the Xonar Essence One’s preinstalled op-amps with its suggested upgrade and, as a high-quality reference, the MUSES configuration. All three configurations sound great especially when compared to typical motherboard-based sound cards, but we found the initial setup using 5532D op-amps to be a little too bassy, with less of a sense of space than either of the alternative configurations. The Burr-Brown op-amps provided a clearer distinction between bass and low mid-range tones. Percussion sounded clear and precise, with accurate positioning, particularly through headphones, which made it sound as if we were in the room with the band.

You very much get what you pay for with the MUSES 01 op-amps. They produced a beautifully balanced sound, with plenty of space and a great deal of subtlety that was particularly audible on acoustic recordings. However, the extra cost of the MUSES version is hard to justify unless you already have top-of-the range speakers and headphones. It may also prove to be more cost-effective to buy the op-amps separately and carry out upgrades yourself.

The Essence One has a C-Media CM6631 audio processor. This handles USB audio transmission, with an Analog Devices ADSP-21261 processor to handle the upsampling. The DACs are a pair of Texas Instruments Burr-Brown PCM1795 chips, but we’d have expected higher-spec DACs, such as Texas Instruments Burr-Brown PCM5102s in a product at this price.

The ease with which you can upgrade the op-amps will appeal to certain users, but may put others off, while the price is certainly daunting.

The Xonar Essence One is a niche product, crossing the gap between hi-fi DACs and USB sound cards. Support for both USB and S/PDIF audio inputs means you can easily connect a computer to hi-fi separates, while the quality of components rivals that of similarly priced DACs without USB support. It won’t suit everyone, but it’s brilliant at what it does.

If you want to make the jump to high-quality audio but find the Essence One’s pricing prohibitive, the Arcam rPAC is a fantastic DAC that has headphone and RCA outputs.