Integrated Amplifiers

Tested in 'Analogue Direct' mode (bypassing the input AK5552 ADC) the gain of the SA30 is as high as many MM phono stages at +49.2dB, though this reduces slightly to +47dB when the line input is digitised at 192kHz/32-bit. The SA30's response is not appreciably different in 'Direct' or 'digitised' mode, the former extending down to –0.3dB/1Hz and up to –0.25dB/20kHz and –4.6dB/100kHz. The 192kHz ADC cuts this off at –10dB/87kHz and –30dB/92kHz. Noise is exceptionally low and the A-wtd S/N ratio some 10dB wider than average at 94.5dB (re. 0dBW) while distortion is also a low 0.0003-0.002% (20Hz-20kHz, 10W). Distortion is fairly constant between 1-10W before rising with output to 0.001%/30W, 0.002%/50W and 0.0035% at the rated 120W/8ohm. In practice the SA30 delivers 2x145W/8ohm and 2x220W/4ohm with the Class G power amp supporting peaks of 190W, 339W, 247W and 130W under dynamic conditions into 8, 4, 2 and 1ohm loads [see Graph 1, below].

Testing the digital stage via the pre outputs is limited to 1.1V because the power amp remains in circuit and, even unloaded, still clips. At 1V/0dBV output, the ESS9038K2M-based DAC stage offers a 104dB A-wtd S/N ratio and minimum 0.00035% THD over the top 10dB of its dynamic range [see Graph 2]. Jitter is suppressed to ~50psec via all sample rates while the rejection of alias images, the amount of pre/post ringing on transients, and the frequency response(s) all depend on your choice of filter. With 48kHz files 'Apodising' gives –1.0dB/20kHz; 'Min. Phase Slow', –5.2dB/20kHz; 'Min Phase Fast', –0.2dB/20kHz; 'Linear Phase Slow', –3.7dB/20kHz; 'Lin. Phase Fast', –0.2dB/20kHz; 'Corr. Min Phase', –12.3dB/20kHz and 'Brickwall', –4.2dB/20kHz. PM