The AM4 volume can be adjusted using sending the following UDP message: "nAD"h0D
Where n = the volume from 0-10 in increments of 1.
These packets should be sent to the IP of the AM4 address with UDP port number 2639.
More details and other commands can be found in our manual on page 20 - 25
http://alcorn.com/wp-content/uploads/2016/04/man_am4.pdf