Network Audio Players/Servers

Evidence for the claim that LPCM inputs are manipulated into a DSD1024/45.5MHz bitstream is supported by the ‘DSD-like’ fingerprint of the DA2i’s technical performance [see boxout, p49]. Most notable is the swell in ultrasonic (requantisation) noise outside of the audioband which necessarily increases the THD+Noise measured at high frequencies [blue trace, Graph 1].

Distortion through bass and midrange is exceptionally low at 0.00017% (re. 1kHz/0dBFs) where the DA2i’s output reaches a high 6.84V in its maximum gain mode. It holds this low distortion over the top 30dB of its dynamic range, dipping to a minimum of 0.00003% at –10dBFs. At 20kHz, THD+N is 0.0005% at 0dBFs, increasing with decreasing digital level to 0.005% at –30dBFs. Other figures, including the wide 116dB A-wtd S/N ratio, the low 28psec jitter [a simple ±100Hz PSU modulation – Graph 2] and low-level linearity good to ±0.2dB over a full 110dB dynamic range, are all illustrative of top-flight performance. Moreover, the DA2i passed our intersample clipping test.

EMM Labs’ digital filter is a ‘shape-shifter’, one that’s linear phase by design but that offers the much reduced time-domain ripples of a slow-roll-off type (close to a NOS type with transient-rich signals) combined with the excellent 106dB stopband rejection of a ‘fast’, high-ripple filter. Responses roll gently away at HF, rather than showing an abrupt cut-off, with all sample rates – reaching –3.0dB/20kHz, –5.1dB/45kHz and –9.1dB/90kHz with 48kHz, 96kHz and 192kHz media, respectively. Low bass response is flat to 5Hz and the DA2i’s source impedance is an equally ‘flat’ 145ohm from 5Hz-20kHz. Stereo separation – a measure of analogue PCB layout quality in this instance – is a wide 125dB (midband), holding to 115dB/20kHz. PM