Integrated Amplifiers

Two gain options are offered here – ‘Lo’ amounting to unity gain (–0.2dB) and ‘Hi’ a more useful +11.5dB. However, as the analogue input is routed via an ES9842QPRO ADC with a limit of 3.1V, in ‘Lo’ mode the HA-L7A’s input margins are comprised before Yamaha’s discrete power amp clips, holding the output to 280mW/32ohm. This improves to 1655mW/32ohm in ‘Hi’ gain mode, well in excess of Yamaha’s conservative 1000mW/32ohm specification, but is restricted to 420mW/8ohm by electronic protection [see Graph, below].

The HA-L7A’s maximum 8.8V voltage output supports 129mW/600ohm (15mW in ‘Lo’ mode) which is more than sufficient for in-ear types. Distortion is very low at 0.0004-0.006% increasing under load at high frequencies to 0.0006-0.02% (re. 10mW/32ohm, 20Hz-20kHz), while the 700mohm output impedance is low enough to maintain a 20Hz-20kHz response to within ±0.1dB into 32ohm. Incidentally, the –3dB/40kHz limit is determined by the ADC’s 96kHz sampling rate (Linear Fast filter). In ‘Hi’ gain mode the A-wtd S/N ratio is a very wide 97.2dB (re. 1V/32ohm) and residual noise a very low –100.2dBV (9.8µV), ensuring inky-black silences with the most sensitive of headphones and earbuds. PM