Network Audio Players/Servers

Although HiFi Rose offers a slightly ambiguous 'max 100W' spec. for the RS201 E, the datasheet for Texas Instruments' TPA3244 PurePath Class D amplifier module suggests a figure of 50W/8ohm in bridged mode. This is realised in the RS201 E at 2x33W/8ohm and 2x60W/4ohm with the same achieved under dynamic conditions, increasing to 105W/2ohm and 100W/1ohm, all at <1% THD [see Graph 1]. Gain is sensibly modest at +28.6dB and the A-wtd S/N ratio above average for a Class D technology at 87.2dB (re. 0dBW). Distortion is very low at ~0.001% through the midrange at 1W/8ohm, increasing slightly to 0.0016%/10W, but rather more abruptly above 10kHz to 0.06%-0.3% at 20kHz from 1-10W. This is a function of the output filter network, as is the 0.08ohm source impedance, increasing to 2ohm/20kHz. The response is very load-dependent – at 20kHz it is +1.1dB/8ohm, –0.4dB/4ohm and –3.5dB/ 2ohm, so loudspeakers with a rising HF load will sound 'brighter'.

The RS201 E's ES9018K2M-based DAC/preamp stage is very 'clean', offering a wide 111dB A-wtd S/N ratio from a maximum 3.15V output and 165ohm source impedance (increasing to 345ohm/20Hz). There's some slight phase noise revealed by the jitter tests but correlated sidebands are suppressed to a very low <15psec (all sample rates). Resolution is good to within ±0.2dB over a full 100dB dynamic range and distortion falls from 0.00160.01% at 0dBFs (20kHz-20kHz) to a min. of 0.0003% over the top 30dB of its dynamic range [Graph 2]. The default digital filter is a standard linear phase type offering a 115dB stopband rejection with response(s) of –0.2dB/20kHz, –1.2dB/45kHz and –2.95dB/90kHz with 48kHz, 96kHz and 192kHz files, respectively. PM