Does the AUX input of the ZK-1001B require a mono or stereo 3.5mm plug?

The Wuzhi Audio ZK-1001B features a standard 3.5mm AUX-IN port. While the amplifier itself is a mono output device (100W to a single speaker), it is designed to accept standard stereo signals from devices like smartphones or MP3 players.

You should use a standard 3.5mm stereo (TRS) plug. The board's internal circuitry typically sums the left and right stereo signals into a single mono signal for the amplifier chip. Using a mono (TS) plug may work but could potentially short one of the output channels of your source device, so a stereo cable is recommended for compatibility with most modern audio sources.