Why do I not compare with the ASUS Xonar Essence STX? As I wrote in an earlier review, this card is potentially better than others but its default opamps are not quite good while my replacements for the I/U stage were deficient in one respect or another. For example, the NJM2114 has a poor control of bass, minor distortions of tonal balance and muddy and loud highs which can be easily heard in recordings of a drum. The NE5532 improves bass sounds, removes the coloring, but does not clean the highs and limits the dynamics. Thus, with every opamp I tested the Essence was inferior to its opponents in some specific parameter but it always delivered a detailed sound, saturated timbres, good spatial resolution and clarity. Could it be the effect of special capacitors? I might have achieved optimal characteristics by buying and testing other opamps and this would have made the Essence even more superior to other sound cards.
Does the Auzen Forte react to opamp replacements? Being unsatisfied with its sound on the first day of my tests, I replaced its LME49720 with AD826 but the difference was negligible. The sound of the AD826 had left an ambiguous impression on me in my tests of the Auzen Prelude, the LM4562 proving a better option.
Having used (i.e. warmed up) the Forte for a month, I made another try and could hear the difference right away. The AD826 makes the smallest details somewhat fuzzy, but creates a good volumetric stereo panorama with a distinct perspective and much better separation of instruments. Vocals and wind instruments are more impressive and bass sounds are more defined. High frequencies are softer and more detailed, but the overall sound acquires a certain melancholy hue I find it difficult to describe.
Next I tried an OPA2132P but not for long because I heard a caricature of music with a toy-like scene and a strong coloring of all frequencies. That was queer because this opamp had done well enough on the Auzen Prelude.
Not hoping for any good outcome, I installed an NE5532P on the card and was surprised once again. This time it was a pleasant surprise. The changes in the sound scene were almost the same as with the AD826.
The older NE5532 could not deliver as high resolution as the newer chip, but was still better than the default LME49720 in some parameters. Frankly speaking, I can’t even explain this by comparing their specs.
And the biggest surprise was when I installed an AD823 which changed the card’s character completely. The lack of micro dynamics and poor echeloning are nonexistent with the AD823! Dynamics is even overemphasized occasionally. The sound scene is drawn very finely (even though not very deep). Environmental acoustics can be heard distinctly. Applause is finally as good as real. String instruments get more realistic, violins being most exciting. The binaural recordings from the Audio STAX – The Space Sound disc were reproduced without a flaw and I was ready to call the AD823 the ideal option for the Auzen Forte but then I quickly realized that most musical albums were irritatingly sharp with this opamp. The tonal balance is shifted into the high-frequency area and the sound is overall too shrill, especially when reproduced via the integrated headphone amplifier. Thus, each of the opamps I tested had some drawbacks and I had to go on looking for an optimal option.
I ordered an LM6172, an opamp with good specs and positive user reports, but it was not quite good, either. One sample of this opamp was as good as the AD826. The LM6172 seems to me to be in between the AD823 and LME49720 in terms of sound quality. It is a little aggressive but good at reproducing vocals. It has rather clean but somewhat too sweet highs, which provoke the feeling of a lack of bass in heavy metal recordings, especially when listening to them via the integrated headphone amplifier. Environmental acoustics are lacking, too, whereas the AD823 reproduced it rather too conspicuously. Yet the more I listened to the Auzen Forte with this opamp, the more I enjoyed the music. It is another case of warming up of electronic components? But this improvement in sound was emerging for a few days and was not related to temperature. By the way, the LM6172 has a wide variance of characteristics (particularly, open-loop gain and common mode rejection ratio), so I recommend you to buy a few samples of this opamp and select the best of them if you want to use an LM6172 with your sound card.
It is the amplifier developed by Auzentech that I can find no fault with. It was better than the Xonar Essence STX’s amplifier with low-impedance headphones (Grado SR 325i) although the Auzen X-Fi Forte 7.1 itself does not sound that good. I could not find an obvious deterioration in sound quality when comparing the Auzen Forte’s integrated amplifier with the C.E.C. HD53R-80 except that the piano was somewhat more realistic on the C.E.C. The integrated amplifier occasionally delivers a better resolution and clearer highs, but it is about the highs that I have some gripes. I guess they are due to the NJM4580 chip employed in the amplifier. The NJM4580 is installed on rear outputs, so its sound can be rather easily learned. Unfortunately, the developer has not provided the option of solder-free replacement for this opamp.
Comparing the rear channels (“Back” and “Side”) with the front output, I could find no substantial difference. Moreover, the front output would often produce a less natural sound with an LME49720 opamp than the rear channels, especially in terms of sound scene depth. As the card was “warming up” and when the opamp was replaced with the AD826, the rear outputs did not seem so attractive, yet offered better micro dynamics and resolution in some recordings. There were some sound defects in the rear outputs such as “graininess” in cymbals, “cardboard” in drums, and suppressed and unexpressive vocals. The same characteristics are typical of the NJM4580 as far as I could examine it with other sound cards, but are not always to be heard. As a result, my preference is divided between the front and rear outputs, which again raises the question whether the dedicated AK4396 DAC is needed on the front output.
I was also curious to check out the professional microphone amplifier of the X-Fi Forte 7.1, so I bought an inexpensive dynamic microphone in addition to my old electret-foil one. To my surprise, the card coped with both microphones well, ensuring a dynamic range of about 60dB on both inputs at a rather high sensitivity. The sensitivity of the front-panel microphone input is half the sensitivity of the professional amplifier whose connector is located at the back panel of the case.
I will not dwell upon the gaming properties of the Auzen X-Fi Forte 7.1 because they are no different from those of any other sound card based on the E-MU 20K audio processor of the first or second version. Everything said on this topic in my previous reviews stays true. I can only add that with the AD823 opamp sound effects and spatial positioning are the most distinct while the background music is not as obtrusive as with the LME49720.