Outboard DACs

At the heart of the Madison Streamer is a 'legacy' 192kHz/24-bit DAC launched by Wolfson Microelectronics in 2009 (Wolfson was acquired by Cirrus Logic in 2014). We last saw the WM8742 DAC in the Cambridge Audio DacMagic 100 [HFN Jun '12] and Cambridge Audio Azur 651C CD player [HFN May '14], the Rega DAC [HFN Jun '12] and Rega Apollo-R [HFN Oct '13], and Lindemann Musicbook 25 [HFN Jun '14]. Wattson is using a pair of these DACs in the Madison Streamer where it boasts a wider 115.7dB A-wtd S/N ratio and lower distortion (0.00025-0.00055% re. 20Hz-20kHz) than was achieved by any of the aforementioned products. Furthermore, distortion falls to a minimum of 0.0001-0.0004% over the top 30dB of its range [see Graph 1] while low-level linearity [red trace, Graph 1] is good to ±0.3dB over a full 110dB dynamic range.

Wattson's balanced analogue output achieves a maximum 4.35V from a 72ohm source impedance but absolute phase is inverted (with volume control set to 'off'), so you may wish to flip the red and black connections to your loudspeakers to restore positive phase. A slow roll-off linear phase digital filter is adopted that trades a limited 5.8dB stopband rejection for near-zero time distortion and responses that roll away to –2.3dB/20kHz and –5.1dB/45kHz with 48kHz and 96kHz files, respectively, but cuts off slightly early with 192kHz streams/files to –3dB/77kHz and –9dB/84kHz. Digital jitter is slightly high at ~1150psec but is almost entirely very low-rate with two ±13.5Hz and ±27Hz sidebands – linked to a specific process inside the Streamer – plus a skirt of uncorrelated phase noise [see Graph 2]. PM