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John Atkinson. Stereophile Jan 2010 said:With all the current fuss about getting audio data from a computer to a standalone D/A processor via S/PDIF, USB, FireWire, WiFi, or Ethernet, it has been overlooked that the oldest way to get audio from a PC is to use a high-performance soundcard plugged into the host machines motherboard. I remember how excited I was when I installed a Sound Blaster Pro 16 board in the 486-based Dell running Windows 3.1 that I was using in the early Clinton era, plugged its analog output into my high-end rig, and played back 16-bit/44.1kHz files.
There are many cards on offer in this sector - ESIs Juli@ (yes, that is how its spelled) and M-Audios Audiophile 192 both seem popular with budget-conscious audiophiles - but I was particularly attracted to the Xonar Essence because it is advertised as having a signal/noise ratio of 124dB, which is true high-end territory. It even comes packed with a typical set of measurements, taken with the same Audio Precision SYS2722 measuring system that I use.
The Essence looks like any other soundcard, with one important difference: its analog output circuitry is shielded by a grounded metal covering this anodized black with a stylized image of a Chinese tiger printed in gold. The cover acts as a Faraday shield, preventing RF interference from contaminating the analog signals.
On the cards exterior is a vertical array of jacks. From top to bottom, on gold-plated RCAs, are the right and left analog line outputs, followed by the headphone on a 1/4" stereo phone jack. Below that, another 1/4" stereo jack serves as both the line and microphone inputs, these selectable with the supplied Xonar Audio Center software. At the bottom is an RCA jack that provides a standard S/PDIF digital output capable of running at sample rates up to 192kIHz. An optical S/PDIF driver is placed at the interior end of the jack, so that a TosLink cable can be used if that is preferred. There is no digital input.
The bottom section of the multilayer card carries the analog input circuitry, this based on a pair of R4580 low noise dual-op-amp Chips, followed by a pair of 5532 dual op-amps. These feed a Cirrus Logic CS538l, a 24-bit A/D converter chip capable of operating at sample rates up to 192kHz and offering a S/N ratio of 110dB. At the bottom right of the card are two ASUS-branded LSI chips that do all audio data processing, including Dolby Digital decoding, Dolby Headphone and Dolby Virtual Speaker processing, and Dolby Pro-Logic II, as well as volume and various reverberation and equalizer functions. Above the larger chip is the power supply section, multiple voltage-regulator chips, chips, a large number of Nichicon Fine Gold electrolytic capacitors, and two purple Sanyo OsCon caps. As well as the attention paid to the power supply ASUS makes much of what they call "Hyper-grounding," which minimizes noise that might degrade the analog input signal.
A high-performance, two-channel 24-bit D/A converter - a Burr Brown PCM l792, the same chip used in Musical Fidelity's V-DAC D/A processor - is sited to the left of the supply section adjacent to a vertical metal shielding strip. The analog output stages lie to the left of this strip and are covered by the removable cover mentioned earlier. Under the cover are two separate output stages, one for the line outs, the other for headphones. The headphone driver is a Texas Instruments TPA6120A2 chip, a current-feedback design capable of sourcing 80mWpc into 600 ohms with very low distortion. The line-level output stage is based on a pair of JRC 2114-D dual-op-amp chips (the 2114D is equivalent to the popular 5532 chip), followed by a pair of low noise National LM 4562 dual op amps.
Although almost all the components used, other than the electrolytic caps, are surface mount types, the four output-stage op-amp chips are socketed 8-pin types, to allow the owner to experiment with other pin-compatible chips.
Installation of the Essence cards in both computers was straight forward; an important point about both cards is that they don't draw power from the PCI or PCI-E slot in computers motherboard. Instead, they have a hard-drive-type 4-pin socket that must be separately connected to the PC's power supply. That way, the analogue circuitry benefits from being maximally isolated from the noisy ground on the PC's motherboard.
John Atkinson. Stereophile Jan 2010 said:It was apparent that the Xonar Essences analogue outputs offered serious sound quality. The DVD-A of Neil Young's Harvest (Reprise 48100-9) drew me into the music, and the blend of James Taylor's and Lindas Ronstadt's voices behind Young on "Heart of Gold" was well delineated without obscuring individuality of their sounds.
Returning to the listening chair, low frequencies had suitable impact and weight, the midrange was uncolored, with excellent clarity, and the high frequencies sounded very clean, with good air around sound sources. In Joni Mitchell's "On France They Kiss On Main Street" (from Shadows and Light Asylum 704-2), the cymbals had an excellent combination of sheen and sizzle without the latter being unnaturally emphasized -although, of course, the HDCD coding was not being applied. And on "The Dry Cleaner Des Moines," Jaco Pastoriu's display of Walking-bass virtuosity Fretless Fender was reproduced with authority, as was Don Alias's kick drum: The balance between the "pat" of the drum-head transient and the "purr" the subsequent body tone was well managed.
The same was true of a 24/96 piano recording I made at the beginning of November for a live-vs-recorded demonstration organized by Philip OHanlon of Luxman and Vivid distributor On A Higher Note (see Stereophile: Live Versus Recorded). I had to record a little closer/drier than was optimal, so that the double hit of the same acoustic was not too disturbing on playback. But the Xonar Essence did a great job of conveying the full weight of the Steinway D as pianist Genadi Zagor pounded it's left-hand keys at the climax of Mussorgsky's Pictures at an Exhibition.
The Xonar Essence STX was doing sterling work for my everyday listening. How would it stack up against other Computer-audio solutions?
John Atkinson. Stereophile Jan 2010 said:The Xonar Essence STX and Essence ST soundcards are by far the least expensive way of turning a PC into a genuine high resolution audio source I have yet encountered. Neither the Essences resolution nor their low levels of noise are compromised by having to operate in the electrically unfriendly environment of a computer chassis. Assuming that the problems I encountered using the Xonar Audio Center to play files at 96 and 192kHz were specific to my computer/operating-system setup, both cards worked reliably, and using the ASIO4 virtual playback device did resolve those problems. However, given the increasing number of high-quality files being offered for download with sample rates of 88.2 to 176.4kHz, their omission is a major impediment to my giving either of these cards a universal recommendation.
And the fact that the Essences are compatible only with PCs is a problem for those who, like me, have found the Mac a more friendly environment for playing music from a computer. But for playing back CD-sources files, I can unreservedly recommend the Xonar Essence, in either of it's guises, as the least expensive means of extracting true high end sound from a PC.
John Atkinson. Stereophile Jan 2010 said:
The STX's frequency responses at sample rates of 33.1, 96, and 192kHz are how in fig.1. A small amount of rolloff (-0.25dB at 20kHz) with 44.1kHz data continues abive the audioband with files of higher sample rates, the only difference between the 96 and 192kHz rates being that the former drops like stone above 46khz. Channel separation (not show) was superb, at 120dB at all frequencies.
Fig.2 shows my usual 1/3 octave swept bandpass analysis of the STX's line output while the card decoded dithered data representing a 1kHz tone at -90dBS with 16- and 24-bit word lengths, and a dithered 1kHz tone at -120dBFS with 24-bit data. Other than an almost negligible component in the left channel at 60Hz, the traces are free from any power supply related spuriae. The increase in bit depth drops the noise floor by 15dB, implying a resolution approaching 19 bits, which is excellent considering the noisy RF environment inside a computer.
I could not replicate the manufacturer's claim of an A-weighted signal/noise ratio of 124dB for the Xonar Essence. however, ref.1V output, I measured 114dB for the STX which is still superb, but 102dB for the ST. It is possible that the actual ratio will depend on the computer in which the card is installed. Even so, the STX's level of noise was so low that the waveform of an undithered 16-bit sinewave at exactly -90.31dBFS was superbly well defined, with both the three DC voltage levels and the Gibbs' Phenomenon "winging" readily apparent, and the waveform beautifully symmetric about the time axis (fig.4). Increasing the word length to 24 bits gave superbly defined sinewave (fig.5).
Word-clock jitter in the STX's Toslink S/PDIF output, measured directly with the AP SYS2722 and a 44.1KHz datastream, was low at 1.48 nanoseconds, which is close to the system's resolution limit. Jitter in the analog output, assessed with Miller Audio research analyser but graphed with the SYS2722, was very low, at 170 picoseconds left and 186ps right, this mainly due to pairs of sidebands at +/-1.63 and +/-3.26 (fig.9).
Nope for 2 channel playback, the D2X is much inferior. Its aimed at a different market compared to the Essence - D2X is more suited for HT.
Thanks Venkat. I've been waiting for a fanless system to arrive in the market that is reasonably priced.
If one wants an audio only system, this would do the trick Intel? Desktop Board D945GSEJT Available Configurations
Currently it is priced @6.5K approx (edit: with 12V DC power). For the computing power to dollar ratio it is overpriced. However with 7K for the sound card, and another 2K for a laptop mini-pic-e 802.11n card + 2K for laptop RAM card, it would be almost the price of a budget CDP with wireless and usb features thrown in. Edit: Bonus is superior HDD based transport. Add 2.5K for 7200.12 barracuda 500GB HDD.
PS: The Xonar D2X is better than the Essence correct?
Sorry, I thought the STX was the PCI version of the D2X which was PCI-E.
Intel sucks yes, which is why I mentioned audio only hapc not htpc.
The big advantage is fanless psu and mobo/cpu with this Intel piddle dribbler
And here I was thinking that was a typo!
Good luck with your HAPC, Gobble.
Nah! If STX is PCI-E it wont fit into the intel dud. Besides rather than spend 18K on another player I would rather get a PMP like S:FLo2 for less than 7K.
Hopefully rockbox will announce firmware to replace the crappy and buggy interface of the S:Flo someday.
What is the purpose of the aux-in 4 pin header on this card? Can I somehow hook up the digital-out of my CDP to this for a A/B DAC comparison? Edit: Aux-in is not digital in?