Hello! What I don't understand is, the assistant of what? With a mixer I guess you mean an audio mixer.
The only thing you are going to have with the mixer is simply an extension of inputs, the auxiliary inputs always handle the same signals, you will have more or less power according to the volume that the device you put in that input handles. The signal from the mixer is equal to that of the auxiliary outputs even sometimes it is already adjusted with a single level, the auxiliaries are banked almost any low level signal that does not saturate said input, it is not recommended to put power amplifier signals, because you are going to spoil the entrance
You're welcome my friend, we are glad to be here to collaborate, I forgot to comment that if the mixers, consoles are in charge of improving and processing any audio signal and give you greater and better gain, but not power, there are currently power consoles which you can put the speakers directly.