MEASURED PERFORMANCE   (measurements: Rohde & Schwarz UPV audio analyser)

Frequency response of the headphone output was flat across the audio band as our white noise analysis shows.  Output measured 0.35V maximum and hiss was high, measuring -68dB with a 16bit signal. These are fair results but the internal DAC / analogue output amps are noisy.
    Results were better via a digital Bluetooth link, frequency response measuring flat to 18kHz with a 48kHz sample rate white noise test signal, as shown. Distortion at 0dB was low at 0.04%. At -60dB distortion was high at 0.6%, but most of this was noise. Ironically, budget all-digital signal transmission channels are often noisy (quantisation noise).
    A 24bit tone gave slightly lower noise and better results (0.4%) but this is nowhere near a 24bit system in linearity terms; it is closer to 14bit. Bluetooth has insufficient data rate to carry high bit depth or sample rate signals, CD quality being its current limit. The HDMI output gave similar results to Bluetooth. NK

Frequency response (-1dB)   10Hz-21kHz

Distortion (24bit)    
0dB        0.04
-60dB     0.6%

Separation (1kHz)     66dB
Noise (IEC A)           -77dB
Output                      0.35V

FREQUENCY RESPONSE, HEADPHONE OUTPUT

FREQUENCY RESPONSE, VIA BLUETOOTH