Among the several aspects which constitute D/A audio signal converter performance is the converter microchip itself. We carefully studied the available technologies and then, only after narrowing down the choices to only the four theoretically best choices, we built a device for the sole purpose of comparing these four technically best converter chips. In our device, all conditions were the same for all converter microchips.
The method LessLoss used to evaluate the sonic differences between these four microchips was as scientific as possible. We used electrostatic loudspeakers and headphones (almost massless) in order to minimize loudspeaker coloration of the signals. The opinions of highly regarded audio enthusiasts and professionals were unanimous. These tests showed that, at least subjectively, the PCM 1704 was easily the best.
Converter Chip Technology
We provide two links, one to the manufacturer of the PCM 1704, and one directly to specific data on this microchip.
Many people do not know that the PCM1704 is classified into different categories of perfection. There is the PCM1704U, which is the least expensive and worst lot. Then there are better ones, which are marked PCM1704U-J and PCM1704U-K at the factory. We would like to stress that the LessLoss DAC 2004 uses only the best and most expensive PCM1704’s. We have chosen the best converter and then use only the best lot of these converters.
There is a fundamental difference between the way parallel multibit converters and the sigma/delta type work. The parallel type use a separate cascade of resistors and switches for each dynamic modulation of the audio signal, whereas the sigma/delta type (or one-bit, as they are also called), rely on a constant comparator to define changes in the audio signal's dynamic magnitude. Each method has its own advantages and disadvantages.
The main advantage of multibit conversion is that they are theoretically less susceptible to the influences of clock jitter. Their main disadvantages lie in their sensitivity to the influences of heat fluctuation.
The sigma/delta microchips have the advantage of being less sensitive to heat fluctuations, however, they react very readily to any amount of clock jitter.
We compared, using the scientific method of 'same thermal and electrical conditions', the Burr-Brown PCM1704U-K (parallel), the Analog Devices AD1862N-J (parallel), the Crystal CS43122 (sigma-delta), and the AD1955 (sigma-delta).
Of course, on the theoretical level all of these microchips are superb. Nevertheless, some differences are evident:
Our empirical tests showed that these differences are indeed audible and that Burr-Brown's PCM 1704 is the very best converter chip in existence today. Earlier achievements in quality such as the legendary PCM63 have been bettered by the PCM 1704.
We provide a picture (300Kb) of the test device used to make this crucial and maximumly objective sonic evaluation.