Can a digital mixing amplifier be connected to a pure power amplifier and then connected to a mixer?

Mini Digital Mixer Amplifier is your good choice.The power amplifier we usually use is called a combined power amplifier. The front panel of this power amplifier can be plugged into a microphone, and the rear panel can be connected to audio input. I don’t know if what I’m talking about is the kind of digital mixing amplifier you are talking about.
If so, then this combined power amplifier can be connected to a pure power amplifier and a mixer.
This type of power amplifier usually comes with a set of signal output ports labeled "REC OUT", which can output signals to other devices.
As for the mixer to connect to such a power amplifier, it is enough to output the mixer signal to one of the audio input ports of this power amplifier. Mini Digital Mixer Amplifier is your good choice.