FYI - The Level shifters on the Audio Mezzi are ‘active’ with speed-up circuits to improve the peak speeds. This is good if you are interfacing with fast devices, but bad if you have a long cable (15cm or more). The outputs of the level shifters break into oscillation when you attach a long cable due to the impedance discontinuity at the end of the wire. if you keep the leads really short (<2cm) the level shifters on the Audio Mezzi work fine.
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