Controlling another MCU's Digital PIN?

Hello All, I was hoping to get some help on the best way to control a Digital Pin on another Microcontorller using the Arduino...

I have an amplifier module that I would like to be able to control through the computer. The Amplifier has an Enable PIN which is HIGH (+5V) when left unconnected, if the PIN is pulled LOW (GND) it will disable the Amp.

What would be the best way to control this PIN from an Arduino?

Thank you all for your help in advance. Kind Regards, Alex.

Do you know how much current flows when pulled low? If it is low enough you could just direct wire the two pins together and a common ground. Take care the pin on the amp really is 5V and not a little higher, that could damage your arduino. If you can’t get a clean common ground or the current or voltage is too high then you could use an opto isolator. If the only problem is high current then use a transistor.