ASUS Xonar Essence STX

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The Xonar Essence STX is a PCI Express x1 sound card manufactured by ASUS.

Xonar Essence STX.jpg

Overview

All specifications are with stock JRC opamps installed.

  • Sample Rates: 44.1, 48, 96, 192 kHz
  • Sample Depths: 16, 24 bits
  • DAC: TI Burr-Brown PCM1792A
  • RCA SNR: 124 dB
  • Headphone SNR: 117 dB
  • Input SNR: 118 dB
  • RCA THD+N: 0.0003%
  • Headphone THD+N: 0.001%
  • Frequency Response: 10 Hz to 90 kHz
  • OS Support: Linux, Windows
  • Full ASIO support at all bit depths/sample rates
  • Supports headphone impedance up to 600 ohms

Config

Linux

If running the PulseAudio sound server, changes are made in /etc/pulse/daemon.conf.
To force the card into 24 bit by 192 kHz mode, uncomment/change/add the following lines:

resample-method = speex-float-7

default-sample-format = s24le
default-sample-rate = 192000

The resample algorithm used can be between speex-float-1 to speex-float-10, where the higher number leads to higher quality resampling. This however takes more processing power and be warned that even the most powerful computers today cannot use level 10. It is recommended to test different values on the system in question.

Windows

Set the bit depth and sample rate to 24 bit/192 kHz by changing the audio device properties via Device Manager.

Fixes

In certain configurations, when clocking the DAC at 44.1 kHz, the output circuit will oscillate in the audible range causing a faint hiss. This has been considered a hardware design flaw by many enthusiasts. The workaround is to force the DAC to 192 kHz sample rate and have the driver upsample all audio. This is desirable in most cases anyway if 192 kHz audio is being played.

Xonar Essence STX No Cover.jpg

The Xonar Essence STX has 3 opamps which are socketed for easy replacement. The unit ships with one LM4562 as the RCA buffer and two JRC 2114D's as the I/V converters. These opamps can be replaced with higher performance ones for an inexpensive upgrade which makes a large difference. Since the LM4562 is only used for the RCA output, if the card is primarily used with headphones, only the 2114D's need replacing. The best replacement is the TI LME49720HA/NOPB in the PDIP package. The part used to be available in the TO-99-8 package, however it has been discontinued. They are available from many vendors including Mouser and Newark. The leads can be cut and bent to fit in the DIP-8 socket on the card. While the LME49720HA's do get hot under normal operation, they do not appear to need cooling.