Integrated Amplifiers

Although Chord offers no specification for its Anni headphone amplifier – aside from a general implication that it leverages off existing, tried-and-tested Chord technologies – the test results are anything but 'ordinary'. Gain is fixed at a modest 5.2dB (x1.8) – a 550mV sensitivity (re. 0dBV) – but this does mean the max. 10.5V single-ended output is only possible from a 5.5V source. Likely? Not really, but as this equates to 184mW/600ohm [black trace, Graph 1 below] your ears will long since have melted. It's also the voltage-clip limit of 3.385W/32ohm [orange trace, Graph 1] – a massive figure and, again, significantly in excess of what's required by even the least sensitive headphones. Using a standard 2V line source, the Anni will deliver 125mW/32ohm which is already the limit of most portable USB headphone amps. Into very low impedance 'phones the Anni is current limited, although 124mW/8ohm [red trace, Graph 1] is generous enough.

Along with the prodigious headroom comes very low noise and an A-wtd S/N ratio of 96dB, improving the Anni's potential for use with very high sensitivity 'phones. The usefully low sub-1ohm source impedance also makes it relatively immune to the peaks and dips of a headphone's load while incurring a minimal 0.1dB signal loss into a standard 32ohm setting. The Anni's native response is tailored, however, with its gentle –0.3dB/20kHz treble roll-off being less significant than the +3.6dB/30Hz low bass boost [black trace, Graph 2]. Distortion, meanwhile, is influenced by loading, particularly at very high frequencies where it lifts from 0.0028%/1kHz and 0.17%/20kHz into 600ohm to 0.003%/1kHz and 0.85%/20kHz into 32ohm at equivalent voltage outputs [blue/red traces, Graph 2]. For a deep dive into the main and highly novel amplifier, see boxout. PM