Headphones

We've tested numerous iterations of iFi Audio's portable headphone amps, including the nano iDSD [HFN Dec '14], the 'Black Label' variant [HFN Apr '18] and EISA Award-winning xDSD [HFN Jul '18], all three incorporating DAC and headphone amp functions. Save for its Bluetooth receiver and companion ES9023P DAC the xCAN is, by contrast, a purely 'analogue' headphone preamp. It's also the most capable, exceeding the 115mW, 175mW and 350mW/25ohm single-ended power output, respectively, of its predecessors to deliver 412mW/

25ohm at 1kHz with distortion falling as low as 0.001% at 10mW output [see Graph 1, above]. A full 3.38V or 19mW/600ohm is available for high impedance headphones while distortion increases only slightly with (low impedance) loading, and only at very low and very high frequencies. So at 1V output there is a lift from just 0.001% to 0.0025% THD at 20Hz and from 0.015% to 0.020% THD at 20Hz between 600ohm and 25ohm loads [black versus red traces, Graph 2 above].

The 'analogue' xCAN's frequency response is not limited by DAC sample rate so reaches out within a tight ±0.1dB from 20Hz-34kHz right up to –1.3dB/100kHz. The usefully low 1.3ohm source impedance also ensures there's almost no change in response when driving low impedance 'phones while the power loss into 25ohm is just 0.35dB. The biggest adaption in bass and midrange response occurs when iFi Audio's XBass/Presence control is used. More importantly, particularly from the standpoint of very sensitive earbuds/headphones, levels of residual noise are very low at –100dBV (10µV), something that is not a given even with battery-powered preamps. The A-wtd S/N ratio is also usefully wide at 99.9dB. PM