Other than OUTLAW, is there a similar company you can recommend for price-performace value?

Also, I have this question. I want to control the volumes individually and swiftly by sliding potentiometers for 10 speakers + 1 subwoofer. I would maybe use a Mackie 16-channel mixer for this.

QUESTION: Where would I interface the mixer for individual speaker volume controls? In-between the incoming audio signal and the preamp/processor? Or in-between the pre/amp processor and the power amplifiers?

Connections would be via XLR-IN and XLR-OUT.

Thanks!