Integrated Amplifiers

Rather than specify an RMS power rating for its Virtus A3, Canor’s 100W/8ohm and 140W/4ohm specification is for ‘IHF dynamic power’. In practice its power output exceeds this at 115W and 220W, respectively, although the stiff PSU regulation means that continuous and dynamic outputs are very similar – 121W, 233W, 427W and 265W into 8, 4, 2 and 1ohm loads, respectively [see Graph 1]. The Virtus A3 is quite power-hungry [see boxout] but otherwise retains a sensible +34.6dB gain (XLR input) with an ‘average’ 84dB A-wtd S/N ratio (re. 0dBW) and a response that rolls gently away at HF, reaching –0.1dB/10kHz, –0.2dB/20kHz and –3dB/100kHz. Distortion is very low, holding to <0.002% from 1-40W before increasing to 0.015% at the rated 100W output (all re. 1kHz/8ohm). Otherwise, THD only increases at HF, reaching 0.03%/20kHz and 0.2%/40kHz (re. 10W/8ohm).

The dual-ES9038 based DAC board offers a maximum 1.6V via the balanced XLR outputs (the A3 clips with peak level digital inputs at volume settings of ‘–7dB’ and higher) from a very low 2-3ohm source impedance. Noise is low, as is digital jitter at <50psec (all sample rates), and the A-wtd S/N ratio is a generous 107dB. Distortion is very low at 0.00014-0.0006% and linearity good to ±0.2dB over a full 110dB dynamic range [see Graph 2]. As ever, response and stopband rejection are determined by which of the eight digital filters (not inc. MQA) are selected. The linear and min. phase ‘fast’ filters reach out to –0.2dB/20kHz, –0.9dB/45kHz and –2.3dB/90kHz with 48kHz, 96kHz and 192kHz files, respectively, while the minimum phase ‘slow’ derivative rolls-off to –5.1dB/20kHz, –7.7dB/45kHz and –9.5dB/192kHz. PM