Asus Xonar Essence STX Reviewhardnrg - May 14, 2009
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The "Hi-Fi" button on the main section of the Xonar Audic Center disables all DSPs and EQ, setting up the soundcard for pure, unaltered sound. I used this for the tests using the line output of the Essence STX, when connected to my M³ headphone amplifier. For the tests carried out using the soundcard's headphone output, I enabled a custom EQ curve to apply an approximate loudness curve, making the sound as perfect as possible, to my ears, on each set of headphones.
I ended up listening to music for two weeks, so the tracks listed below are just a few of the many I listened to while setting up the EQ for each headphone, and enjoying countless hours of high-quality sound and music. The first two are from electronic genres, the first a heavy, slamming dancefloor-oriented track, and the second a much more laid-back musical piece. The next track is a Celtic style song with Eastern influenced instrumental arrangements. The final track is a classical piece, there are no vocals and no electronic gear, just traditional instruments.
All the tracks were ripped from CD using ExactAudioCopy, encoded to the lossless FLAC audio codec. This means the exact bit-for-bit signal of the CD track is maintained and reproduced upon playback. The advantage in regard to this test is that there is no noise from the optical disc drive whilst listening to the music. Foobar2000 was used as the media player as it supports ASIO playback.
Since the Xonar Essence STX is in a different league to the Xonar D1 and onboard sound, I decided to limit my testing to comparing it to my modded X-Fi XtremeMusic.
- Xonar Essence STX: Playback @ 75% (±0 dB), Master levels @ 100%, foobar2000 output = ASIO, 16 bit, 6ms
- X-Fi XtremeMusic (modded): Wave @ 75% (±0 dB), Master levels @ 100%, foobar2000 output = ASIO, (auto 16 bit), 5ms
- Léger & Lake - "Aqualight"
- Schiller - "Das Glockenspiel" (Schill Out Mix)
- Loreena McKennitt - "The Mystic's Dream"
- Camille Saint-Saëns - "Aquarium"
X-Fi line-out to M³ headphone amplifier
This is my current high-end listening setup. I built the headphone amplifier myself and tailored the bass boost section for the AKG K 701 headphones, and my preference in tonal balance. The kick drum beats in "Aqualight" are powerful, deep and clean on the K 701, but a touch too emphatic with the HD25 (due to the tailored bass curve of my M³ amp). The synth pads and glockenspiel hits in "Das Glockenspiel" echo and fill my aural periphery with lush and dream-like wonder on the K 701, the HD25 feels a little bit more enclosed yet still just as detailed. The vocals of Loreena and the choir in "The Mystic's Dream" are quite breath-taking. I like the flute, piano and string sounds in "Aquarium," and from the X-Fi I again feel like I'm in an enhanced state of mind.
Essence STX line-out to M³ headphone amplifier
Swapping to the Xonar's line out, it quickly became quite apparent that distinguishing the difference between my modded X-Fi XtremeMusic and the Essence STX would be difficult at best. This is probably due to the fact that I replaced the op-amp on the X-Fi with an LM4562, the very same as the one on the Xonar. The differences are down to the capacitors and DAC on each card. I would say that overall, the Essence STX has a slightly purer sound, the XtremeMusic seems as though it has a touch of tube-like distortion in comparison. Interestingly, the X-Fi appeared to have a slightly wider stereo image than the Xonar, and this correlates with the Stereo Crosstalk tests conducted with RMAA after the listening tests.
Essence STX headphone output
With the K 701, at first I thought the onboard headphone amplifier of the soundcard was somewhat lacking, kick drums didn't seem to hit as hard, consonants in vocals weren't as pronounced as when using the M³ amp. However, despite the low impedance (62 Ω) of the K 701, they are notoriously harder to drive than you would suppose. Increasing the gain to High Gain (+12 dB for 64 to 300 Ω) in the HP Advance Setting provided much more dynamism, so much so that I was actually taken aback by the difference. There was much more bass slam in "Aqualight" and all the heavier electronic music I listened to, and there seemed to be an almost endless reserve of bass when using the HD-25 in particular.
I think critical listening of music is the most telling test of a soundcard's sound quality, and the Xonar Essence STX's performance was stellar. Whether listening to music through speakers, an external headphone amp, or using the onboard headphone amplifier, music lovers and audiophiles will definitely enjoy the experience. As I mentioned, the music test was extensive, and I would say that I still prefer my M³ headphone amp and AKG K 701 headphones, but the margin is fairly small. I have to point out that I customised my amp to the sound of the K 701 headphones. This is apparent when using the Sennheiser HD25-1 II headphones. The bass curve I implemented in the M³ amp accentuates the mid to high bass frequencies a bit too much, so even though it is a variable bass gain, it just doesn't work as well as using the Essence STX EQ controls.