Spectrograms for VIA VT1616
There are a few things to note about the VT1616. This low SNR and high distortion may be the results of an improper wiring layout of the components of the audio subsystem on the mainboard. The manufacturer didn’t find a better solution than place the digital part (the VT1720 audio-controller) on one end of the PCB, and the analog one (the VT1616 codec) on the other. The codec itself is quite far away from the audio connectors, too. That’s why the crosstalk affected the quality of sound; this is quite clearly shown on every spectrogram. Note the parasitic oscillation (up to -80dB) at the 50Hz mark. This is nothing else but the effect of the crosstalk between the audio-signal paths and the power circuits. “Thanks” to them, the sound quality characteristics were lowered.