Cambridge Audio DacMagic

Each channel of the DacMagic has its own Wolfson WM8740 DAC and analog circuits that are both dual mono and balanced. The DacMagic therefore has XLR outputs in addition to RCA jacks. Thanks to DSP (Digital Signal Processing), a unique digital filter circuit, additional jitter suppression and upsampling to a higher sample rate were made possible. The DSP IC is a Texas Instruments 32-bit type that uses asynchronous upsampling with ATF (Adaptive Time Filtering). That ATF is actually one of the DacMagic's most important trump cards, because the resampling process has a higher precision than that of most sample-rate converters. The Cambridge DacMagic ATF DSP uses an algorithm that approximates the original signal more closely than conventional interpolators and can upsample to 192 kilohertz (24-bit), according to the manufacturer. Thanks to the 32-bit DSP IC, Cambridge Audio has been able to develop its own digital filter algorithms with three different filter options. Users can choose between linear phase, minimum phase and steep filtering via a button on the front panel. Linear phase provides the same filtering as that of the Azur 840C upsampling CD player. Thanks to constant group delay, the signal is presented completely time-coherent at the output. Minimum phase does not offer a constant group delay but ensures an optimal reproduction of transients (percussive sounds). Steep filtering removes intermodulation products (close-in aliasing) from the useful frequency range by causing the frequency response to drop from a slight roll-off at 20 kilohertz to an ultra-steep roll-off. All three filters are of high quality and give the user the option to choose between subtly different reproduction characteristics, according to the manufacturer. The filter settings are, by the way, remembered per digital input, so that one can, for example, choose steep filtering for the USB input and minimum phase filtering via the S/PDIF input. In addition, the DACMagic offers a feature that we have not encountered in affordable DACs for a long time: the ability to invert the phase of an input, which allows recordings with a (180-degree) inverted phase to be reproduced correctly, among other things.

On the 5-millimeter-thick aluminum front panel, in addition to the two buttons for input selection and filter modes, we also find several indicator LEDs that indicate the sampling rates (32, 44.1, 48, 88.2 or 96 kHz). Phase inversion is achieved by holding down the filter selection button for a few seconds. At the rear, in addition to two dual-purpose (S/PDIF & Toslink) inputs and a USB input, there is even a dual-purpose digital output (also S/PDIF & Toslink). Sources such as a PC/NAS or a Media Player (so also docking stations) can be connected directly. The analog outputs are designed as both unbalanced (RCA jacks) and balanced (XLR chassis), which is remarkable. The 18 VA power adapter is equipped with a ferrite bead (RF stopper) at the end of its cable.