Rational and clear information regarding audio equipment is not available today from mainstream audio literature. We only see unnecessary long treatises on high end audio, concentrating on technical descriptions and pointless analyzing of sound nuances, without any clear statements about the sounds fidelity.
Just like external sound cards, USB D/A converters are an integral part of computer audio systems and we would very much like to present our view of their performance. We are trying to avoid long descriptions by organizing USB converters into 3 classes, thus making the information about them simple and decisive. Placing all USB converters into only 3 groups may seem superficial, but after the following explanations the point shall be very clear:
CLASS 1 converters do not change the characteristic sound of acoustic instruments significantly. Trained or professional ears can easily determine the level of distortion caused by the digital to analogue conversion.
CLASS 2. The majority of USB D/A converters are members of this group. CLASS 2 converters lightly distort the analogue signal in a way usually referred to as “digital sound”. It is easily recognized in crescendo passages of orchestral music.
CLASS 3. Artificial sound, the annoying and unnatural timber of acoustic instruments, make the converters in this class completely useless for serious stereo systems. Although some modern music genres like techno-pop could even profit from distorted sound that the class 3 USB DAC can produce, music connoisseurs devoted to high fidelity should not be interested in digital mish-mash, produced from CLASS 3 converters.