Integrated Amplifiers

While the H400’s preamp and digital board are clearly updated over the H390 [HFN Aug ’19], the very capable Class A/B power amp is largely unchanged – it still delivers in excess of its 250W/ 8ohm rated output to the tune of 2x265W/8ohm and 2x480W/ 4ohm with 270W, 529W and 1.01kW available at <1% distortion under dynamic conditions into 8, 4 and 2ohm loads [Graph 1].

This is all but identical to the H390 except that Hegel has now given the amp its head into very low loads, relaxing the current limit to deliver 1.77kW (42.1A)/1ohm in place of the H390’s 1.16kW (34.1A). Power is still channelled through a low 0.016-0.048ohm source impedance and with a response that’s flat to within –1dB from 6Hz-70kHz (–1.7dB/100kHz). Noise remains very low too, the H400 matching the H390’s sensibly moderate +32.6dB gain (balanced input) and contributing to a generous 90dB A-wtd S/N ratio (re. 0dBW). THD is low, climbing gently with output from 0.001%/1W to 0.005%/10W and 0.018%/100W at 1kHz, increasing to 0.007%/10W at 20Hz and 20kHz.

The digital board is based on the H600 [HFN Oct ’23], with an ES9038Q2M DAC and Hegel’s choice of minimum phase filter, offering an 83dB stopband rejection. Via the fixed (2.4V) line out, the response shows a mild but consistent HF lift with all sample rates, reaching +0.2dB/20kHz, +0.75dB/45kHz and +1.7dB/90kHz (and +2.0dB/80kHz) with 48kHz, 96kHz and 192kHz media, respectively. THD is 0.0003-0.0018% (20Hz-20kHz) with peak (0dBFs) digital inputs and falls to a minimum of 0.0001-0.0006% over the top 30dB of its dynamic range [see Graph 2]. The 102.3dB A-wtd S/N ratio is a little under par but jitter is supremely low at <5psec at all sample rates. PM