Pre/Power Amplifiers

Rated at 125W/8ohm, the A 200 romps home with 145W/8ohm and 285W/4ohm although, as the dynamic profile illustrates [Graph 1], there's a jump in distortion from a very low 0.0005%/1kHz at 1W-110W to 0.3%/115W, 0.5%/120W and finally 1% THD at 145W. The Class D architecture dictates that continuous and dynamic power is almost identical – 146W, 289W, 290W and 152W into 8, 4, 2 and 1ohm loads, respectively, limited to ~12A into low impedances. Distortion also increases with frequency although a figure of 0.01%/20kHz (re. 10W) is still low – all courtesy of the Purifi Eigentakt Class D modules [see NAD M33, HFN Aug '20]. This advanced amplifier module also delivers the load-independent ±0.15dB/20Hz-20kHz frequency response and wide 88.4dB A-wtd S/N ratio (re. 0dBW) that sets the A 200, and other 'Eigentakt adoptees', above the standard Class D pack. The switchable DF (damping factor/output impedance) is a T+A 'feature' however – from 0.023ohm (low) to 0.12ohm (high).

Meanwhile, the DAC 200 – sharing its digital 'heart' with the HA 200 [HFN Aug '20] – offers a huge 15.2V max. output (XLR), albeit achieved at '–2' on the volume scale with a peak level 0dBFs input (the output is clipped at higher volume). The A-wtd S/N ratio reaches 116dB here, with distortion peaking at 0.0029-0.0034% (20Hz-20kHz) before falling back to a minimum of 0.00012-0.00035% over the top 20dB of its dynamic range [see Graph 2]. Low-level linearity holds good to within ±0.1dB over a full 110dB dynamic range while jitter, with the 'local oscillator' engaged, is fully suppressed to ~10psec across all inputs and sample rates. I discuss the impact of the six digital filter modes on time domain and frequency response in our Consonant Coefficients sidebar. PM