Integrated Amplifiers

I compare the performance of the X5 with the X3 in our boxout so I'll keep this report focused on the X5 as a solo product. Rated at 350W and 600W into 8/4ohm, respectively, it succeeds in delivering 2x450W/8ohm and 2x775W/4ohm at <1% THD with sufficient headroom to support 530W, 1.02kW and 1.15kW into 8, 4 and 2ohm loads under dynamic conditions, but limited to 590W/1ohm [see Graph 1, below]. Gain is a moderate +31.3dB (more 'useable' than the 40dB+ of many integrateds) but the A-wtd S/N ratio is below the industry average at 80dB (re. 0dBW).

Distortion is low and steady with output at 1kHz from 0.004%/1W to 0.0045%/10W, 0.005%/100W and 0.006% at the rated 2x350W/8ohm (drawing 1.15kW from the wall at this point). THD is impressively unperturbed with frequency too, holding to 0.004-0.005% from 20Hz-10kHz across 1W-100W/8ohm. Output impedance is a low 0.014-0.075ohm (20Hz-20kHz) and the response tailored through presence and treble to –0.8dB/20kHz.

Measured via the pre outs at 2V, the digital inputs are all subject to a minimum phase digital filter that trades reduced time domain distortion for a poor ~5dB stopband rejection and tailored HF response. The latter drops to –4.9dB/20kHz (or –3.3dB/20kHz with 48kHz files), with –5.9dB/45kHz and –6.9dB/90kHz realised with 96kHz and 192kHz digital files. Jitter is a little higher than average at 550-600psec and the A-wtd S/N slightly lower than expected at 104dB but low-level resolution remains true to a tight ±0.15dB over a 100dB dynamic range. Distortion is a low 0.0009-0.0085% with peak level (0dBFs) digital inputs (20Hz-20kHz), falling to a minimum of 0.0002-0.0009% at –10dBFs [see Graph 2, below]. PM