Which output port of an amplifier is safe to record with an Android?

Hi,

How do you intend to record on the Android phone?

It appears that the only options to record on the phone would be to use the phone's microphone or perhaps an external microphone or wiring connected to the phone’s headphone jack. Although I’m not sure if the phone also has the option to accept audio through the USB-C port or not. It may depend on the available settings in the phone e.g. audio accessory mode.

If using the microphone you would need to record from speakers connected to the amplifier.

If using the headphone jack you need to connect from the pre-out (either one) to the headphone socket microphone wiring pins on a 3.5mm jack plug, which is then plugged into the socket.