Asus Xonar Essence STX Review

Testing:

I disconnected all the fans, even the CPU heatsink fan, and was left with just the PSU fan. The PSU fan emits a soft sound, it is pretty much inaudible in terms of fan noise. The noise from the hard disks both from idle and seeking vibrations was too annoying to ignore, so I took them all out and laid them on small rectangles of sound-isolating foam/sponge. The door to the room was closed during testing, and with no other equipment running, you could literally hear a pin drop.

The two most intriguing features of the Xonar Essence STX to me are the onboard headphone amplifier and the purity of the line-out. I wondered how the soundcard's amplifier would compare to my own custom made Class A headphone amplifier. I am also interested in seeing how it measures up to the line-level output of my modified XtremeMusic soundcard. Following cotdt's guide at head-fi.org, I have upgraded the front stereo line-out's op-amp and the power capacitor, as well as bypassing the decoupling output stage, to raise the sound quality to about the highest possible.

Testing Setup:

• Processor: Intel Q9450 Core 2 Quad 333x8
• Heatsink: Noctua NH-U12P with Noctua NF-S12-1200
• Motherboard: Gigabyte X48-DS4
• Memory: 2 x 2GB Mushkin XP2-8000 Redline 5-5-5-12
• Video Card: Sapphire HD4850 with Arctic Cooling Accelero S1 rev 2 (passive)
• Sound Card: Asus Xonar Essence STX
• Power Supply: Mushkin 800 watt Modular power supply
• Hard Drive: 1 x Hitachi 7K250 160GB SATA
• Hard Drive: 1 x Hitachi 7K250 200GB ATA
• Hard Drive: 1 x Samsung T166 500GB SATA2
• Optical Drive: Sony DDU1612 DVD-ROM
• OS: Windows Vista Business Edition SP1 64-bit

Comparison Sound Cards:

• Realtek ALC889A High Definition Audio codec (onboard audio)
• Asus Xonar D1
• Creative X-Fi XtremeMusic "Hotrodded"

Listening Gear:

Headphones:

• AKG K 701 Reference Headphones (powered by M³ Headphone Amplifier for line-out mode)
• Sennheiser HD25-1 II

Interconnects:

• Soundcard to amp: Custom made Van-Damme / Switchcraft / Neutrik with silver-plated OFC + OFC conductor, OFC shield
• Soundcard loop-back: an identical cable, but using a 3.5mm to 2x phono/RCA adapter, or 3.5mm to 1/4" jack adapter

Benchmarks:

• Audio:
  1. RightMark (RMAA)

Subjective Listening:

• Audio:
  1. Music
  2. Games
  3. Movies