Integrated Amplifiers

Comparing this 150W/8ohm-rated CSA150 with the 100W/8ohm CSA100 [HFN Aug '20] is instructive because the former behaves almost exactly like the latter except for an uplift in continuous power output. So, where the CSA100 offered 2x125W/8ohm and 2x193W/4ohm, the flagship CSA150 delivers 2x175W/8ohm and 2x270W/4ohm. However, the PSU has proportionally less headroom so its dynamic output of 184W, 341W, 570W and 767W into 8, 4, 2 and 1ohm [see Graph 1] is not appreciably higher than the 174W, 320W, 527W and 715W, respectively, offered by the CSA100. The trend of distortion – still largely 2nd harmonic – also increases uniformly with power output through the midrange from 0.003%/1W, 0.008%/10W, 0.03%/100W and 0.04% at the rated 150W (all 1kHz/8ohm) although, at very high frequencies, it's a consistent ~0.04%/20kHz (1-100W). As we saw with the CSA100, the CSA150's A-wtd S/N is a below-average 80dB (re. 0dBW) but this is still a pleasing white noise rather than hum or buzz. The (analogue) response remains flat and extended from +0.0dB/5Hz to –0.25dB/20kHz and –2.7dB/100kHz while the main/preamp outputs are still phase inverting.

Measured via the non-inverting tape loop, a 0dBFs digital input yields a 2.08V output, the ESS9018S-based DAC stage offering a 103dB A-wtd S/N ratio and minimum 0.0011% THD over the top 20dB of its dynamic range [see Graph 2]. Jitter is suppressed to an impressive ~30psec via all sample rates while the 82dB stopband rejection, ringing on transients, and response(s) are all defined by the default linear phase digital filter. The responses reach to –0.04dB/20kHz, –0.7dB/45kHz and –2.3dB/90kHz with 48kHz, 96kHz and 192kHz digital files. PM