Well here is my take on decent gain structure after the console.
Find out the maximum(clipping) input and output voltage/level in dBu/dBv/dBm(you have old gear 0_o) of all your equipment, let's go with what I have in one of our rooms.
Yamaha MG32fx: +24dBu output
DBX 223xs +22dBu input: +21dBu output
QSC RMX2450 input +4dBu
Now to start off with we can see that the input sensitivity of the MG32fx and the DBX223xs is very similar and to adjust the input attenuators of the DBX unit down 2 db is really a pointless exercise IMHO but can be done. The biggest thing here is the output of the 223 is 21dBu but the input sensitivity of the RMX2450 is +4dBu, this will cause the clip point of the amp to sit way below that of the rest of the system, the easiest way to fix this would be to turn down the output of the 223 by 17 dB or to turn the input attenuators on the RMX2450 down by 17dB... I would honestly do this at the 223 instead of the amp but as far as I know it shouldn't make a hell of a lot of difference...
You would if you had limiters in place set the limiter to not allow the amp to receive enough input voltage to allow the speakers to exceed their peak power rating but that is a whole other story, you should also not be slamming into your limiter that whole time, it is there to protect your speakers from sudden spikes like a dropped mic, not there to control your fingers.
If there is any mistakes in this please call me out and I will edit it.