Network Audio Players/Servers

While the RAS-5000 follows fairly traditional ‘Rotel amplifier’ thinking, it is not a carbon-copy of the RA-1592mkII integrated which mustered 2x225W/8ohm and 2x425W/ 4ohm with sufficient headroom to support 307W, 585W, 1.08kW and 1.76kW into 8, 4, 2 and 1ohm loads (<1% THD) under dynamic conditions. Instead, the RAS-5000 is necessarily slightly scaled back, offering 2x160W/8ohm and 2x245W/4ohm with a dynamic output of 221W, 422W and 758W into 8, 4 and 2ohm loads. Output is protected in low 1ohm loads at 336W [see Graph 1, below]. Overall gain is a sensible +32.4dB and the A-wtd S/N ratio a wide 93dB (re. 0dBW) while distortion, though admirably ‘flat’ vs. frequency at 0.001-0.003% (re. 10W, 20Hz- 20kHz), does track upwards with output from 0.001%/1W to 0.003%/10W, 0.03%/30W and 0.05%/100W (all 1kHz/8ohm). The output impedance is a uniform 0.025ohm from 20Hz-10kHz, rising thereafter, while its ‘analogue’ response reaches out to –0.08dB/20kHz and –0.55dB/100kHz.

The S/PDIF and USB inputs are handled by an ES9028 DAC configured here with an external medium-tap, minimum phase upsampling filter that delivers just 12dB of stopband rejection with responses that reach out to -0.5dB/20kHz, -9.7dB/45kHz and -5.3dB/90kHz with 48kHz, 96kHz and 192kHz digital files. Tested at 2V output from the preamp RCAs, the RAS-5000 offers an above-average 108.5dB A-wtd S/N and low <45psec jitter (all sample rates). Distortion rather 'flatlines' at ~0.01% over the top 40dB of its dynamic range [see Graph 2] though, subjectively, this is no bad thing, especially as its low-level resolution is good to ±0.1dB over a full 100dB dynamic range. PM

Above: Dynamic power output versus distortion into 8ohm (black trace), 4ohm (red), 2ohm (blue) and 1ohm (green) speaker loads. Max. current is 13.8A

Above: Distortion versus 48kHz/24-bit digital signal level over a 120dB range (1kHz, black; 20kHz, blue)