A high-quality audio section and an acoustically appropriate environment are necessary to compare the sound produced by audio cards of such a high level. I didn’t have such an environment and had to use high-quality headphones instead (Grado SR 325i and Beyerdynamic DT 770 Pro) together with a C.E.C. HD53R-80 amplifier and a Monster Standard Interlink 200 cable.
This class A amplifier has a low harmonic distortion factor (the manufacturer claims it to be 0.009% but my measurements showed 0.019% at 2V on the output) and easily copes with both the low-impedance Grados (32Ohms) and the high-impedance Beyerdynamics (250Ohms). The audio cards’ line outputs work worse with the headphones: the crosstalk grows up considerably, and the frequency response changes greatly at low and high frequencies. Intermodulation distortions get higher, too. Thus, it is not correct to compare the audio cards when connecting the headphones directly to the line output because each of them responds differently to such a load.
Comparing the sound of the Auzen X-Fi Prelude with and without the C.E.C. amplifier, I could note the worsening of the dynamics as well as the precision and dimensions of the scene. The lower the load resistance was, the more evident the amplifier’s advantage grew, also in terms of sound volume – the signal level at the card’s output goes down with a low-resistance load and fluctuates due to the irregularity of impedance relative to frequency. It seems that some of the electrolytic capacitors near the output filters are connected into the signal chain because the same headphones connected to the FP_Audio output (as I wrote at the beginning of the review, this output is connected to the operation amplifier via a 47µF capacitor) sound much louder. Subjectively, the OPA2134 loses detail not so much, so if you have to use headphones without an external amplifier, try connecting them to any of the rear outputs and send the sound to the necessary channels by means of ASIO.
With the C.E.C. amplifier the card sounded fantastically. I couldn’t believe my ears when I heard it first – familiar compositions were so unusual. Scorpions’ Holiday, Gary Moore’s Always There For You, Roger Waters’ Too Much Rope – I always use these compositions for a quick test of sound quality – they all acquired new details and surprised me with natural sounding. I listened through all my collection of test compositions and found nuances, previously unattended to, in every one of them. Interestingly, I had no doubt that each nuance that sounded differently was the correct sound while the audio cards I had listened to before were unable to reproduce it with such mildness and harmony.
The Auzen X-Fi Prelude creates an unbelievably realistic scene, filling it with the deepest bass and natural reverbs with precisely positioned instruments. Minutest details are reproduced in the sound of each instrument. Coupled with the excitingly accurate reproduction of space and distance, this delivers an unforgettable presence effect. The LM4562 was reported to produce a clear uncolored sound, yet I didn’t expect such a outer-space clarity. There are no screens between the listener and the music, and high-quality live recordings provoke an impression that you are indeed in the area where the concert is going on.
The sound from the other line outputs, serviced by the OPA2134 amplifier, is very good, too. The scene and details at mid-frequencies are close to those of the LM4562, but there is no such an impressively voluminous bass. High frequencies sound slightly different, too. Still, I guess this sound is preferable to the sound of the Creative X-Fi Elite Pro. The latter is no worse in terms of details, but produces a bright, somewhat lifeless sound. The Creative card copes much better with headphones attached directly to the line output, though.
The operation amplifier can be replaced without soldering, and I tried to figure out the reason for such a sound of the Auzen X-Fi Prelude by checking it with two operation amplifiers from Texas Instruments I had at hand. The OPA2132P sounded alike to the OPA2134 installed on the rear channels but it seemed somewhat worse at high frequencies and closer to the LM4562 in the deepness of the bass. With a NE5532 the card sounded no better than others – flat, bright and less detailed.
The sound remains clear but loses its precision and spaciousness without the Bit-Matched Playback option or in the Entertainment mode. The Crystalizer effect changes the frequencies somewhat, but kills the scene, so I guess this widely touted technology is only really useful in the Game mode where the sound of music is distorted seriously: it is not a pleasure to listen to music even with such effects as EAX, CMSS-3D, SVM and Crystalizer disabled. The sound is dull and non-dynamic, and becomes just unbearable if you enable CMSS-3D Headphones.
The gaming capabilities of the Auzen X-Fi Prelude 7.1 are the same as those of Creative’s cards with the X-Fi audio-processor, so I don’t want to discuss them at length here. I only want to note that you should enable CMSS-3D for HRTF processing, but the quality of Creative’s 3D sound is greatly overstated in my opinion. In the 2/2.1 Speakers configuration the sound is jerky when the hero is turning around, with the volume suddenly jumping from channel to channel (you can hear the audio stammer in the speaker test where a helicopter’s flyby around the gamer is simulated). In the “CMSS-3D headphones” mode the sounds are muffled, the distance is reproduced incorrectly and the timbre is greatly distorted. The helicopter demo sounds perfect, but I couldn’t hear such positioning in games. Moreover, it is much better to play Crysis with the 2/2.1 setting than with the Headphones.