Reviewed on: SoundStage! Solo, July 2020

I measured the iFi Audio Hip-dac using Audiomatica Clio FW 10, QuantAsylum QA401, and Neutrik ML-1 audio analyzers, and TrueRTA spectrum analyzer software. Note that my focus with these tests is on measurements that confirm these devices’ basic functionality.

In addition to Diego Estan’s SoundStage! Solo review, I’ll state that I have been using the Hip-dac for a few months and have found that it sounds very good and can deliver excellent sound quality with all my headphones (including the very-low-sensitivity HiFiMan HE6se open-back headphones, which, with most music recordings, it can drive to a moderately loud level at full volume). The only problem I had with it is that the USB connection with the supplied cable was sometimes intermittent with my Lenovo laptop, a problem I attribute to the cable.

Frequency response unbalanced

This chart shows the frequency response in the left and right channels at a 96kHz sampling rate into 32 ohms from the unbalanced output. Response is 0.0dB at 20Hz, -0.05dB at 20kHz, and -0.24dB at 40kHz, all referenced to 0dB at 1kHz. From the balanced output (not shown), the results were -0.26dB at 20Hz, -0.13dB at 20kHz, and -0.37dB at 40kHz. Channel level was about 0.2dB lower in the right channel. Output into 250- and 600-ohm loads was practically identical. Pretty good all-around -- this DAC-amp is not going to change the tonal balance of your headphones.

Frequency response xBass

This chart shows the function of the xBass button. The bass boost starts to happen below 300Hz or so, rising to 4.5dB at 100Hz and 11dB at 20Hz.

THD unbalanced

This chart shows the unbalanced output of the Hip-dac vs. total harmonic distortion (THD) into 32-, 250- and 600-ohm loads at 1kHz. (Note that I produced this chart on the QA401, but the results below come from direct measurements from the Clio 10 FW; as the QA401 is new, I’m still learning to use it and thus trust the Clio numbers, but the chart does show the shape of the THD vs. power curves accurately.) Rated power from the balanced output is 280mW into 32 ohms and 3.2V (17mW) into 600 ohms, both at 1% THD (frequency unspecified). Into 32 ohms, I measured output of 267mW at 1% THD and 252mW at 0.5%. Into 250 ohms, at maximum volume with a 0dBFS sine wave, output is 38.5mW at 0.008 THD, and into 600 ohms under the same conditions, the numbers are 16.1mW at 0.007% THD. So my results are at most 0.39dB lower than iFi’s.

THD balanced

This chart shows the balanced output of the Hip-dac vs. total harmonic distortion (THD) into 32-, 250- and 600-ohm loads at 1kHz. Rated power from the balanced output is 400mW into 32 ohms and 6.3V (66mW) into 600 ohms, both at 1% THD (frequency unspecified). Into 32 ohms, I measured output of 420mW at 1% THD and 340mW at 0.5%. Into 250 ohms, output is 109mW at 1% THD and 107mW at 0.5%, and into 600 ohms the numbers are 50.5mW and 47.7mW, respectively.

Distortion

Here you can see the harmonic distortion spectrum and noise floor of the Hip-dac. I’m showing two versions because the profile changes as the amp goes into clipping. The first is referenced to 163mW, the second to 259mW, both into a 32-ohm load. At high levels just below clipping, third-order harmonics are stronger than the second-order harmonics, but at full clip they’re more or less balanced. Remember, though, that it’s unlikely you’ll even push this amp into distortion; even at full-crank with the HiFiMan HE6se’s (the least-sensitive headphones I have), the Hip-dac did not produce audible distortion.

Output impedance is not rated. At 1kHz, I measured 0.2 ohm from the unbalanced output, which won’t contribute significantly to total impedance and will thus have no audible effect on the response of your headphones.

. . . Brent Butterworth
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