You dont need the 2nd module.
Run the trigger out to the coil and use the line side to break the 120V hot using common and normally open terminals. Run the neutral directly to the silver screw on all your receptacles. The switched hot off the N/O terminal on the relay will go to all the brass screws on your receptacles. You are limited to 10A with that relay's line side contacts. Since it is controlling 4 devices with capacitor inrush you might run into problems, might not. We always upsize relays to a contactor for power loads like this.
Neat little project!
Again, a current sensing strip will save you a lot of headache. Plug your AVR into the master and all your subs and amps into the switched receptacles. There are 2 always on receptacles to run a cooling fan or light etc. 40$
https://www.amazon.ca/APC-P8GT-Power-Sav...G5S3MX3R7GZR926
