@PVC The only audio settings for the Ignite set-top box are in Settings / Device Settings / Audio"
On your old Digital TV set-top box, did you happen to change the "audio range" to Narrow and could that be why its output levels were different? On Ignite, is the audio level different on another channel or is it consistent on all channels? Do you hear any difference in volume if your change HDMI Audio Output to Stereo (PCM)?
I would say it's generally consistent across channels. The 4K music video channel is probably the worse.
Doesn't make a difference if I switch to Stereo or Expert mode.
Is there some sort of gain/volume setting on the box itself, e.g., similar say to an Android TV box that has its own volume? When I hit volume up on the rogers remote it wants to try and use the TV volume.
Are you using the same input on the AVR for Ignite as before? Some AVRs allow you to vary the volume by input, thereby equalizing the volume across a number of devices that may have different output volumes. I know that on my Denon, I've adjusted each of the many inputs to equalize the volume on DVD, BD, Phone, Tape, VCR, PVR, TV, etc. I'm not sure if this is possible in your Anthem, but it should be somewhere under user settings and even if you don't need to equalize with other equipment, you may be able to boost the volume of the Ignite input.
Are you seeing (hearing) the same thing on recordings as on live TV. For example, recordings are presented to the Ignite box as improperly encoded DD5.1 with only the LF & RF channels active. This would make for a lower volume than live or OD programming. For recordings, to get surround sound you'd need to set the Ignite box to "stereo" to allow the AVR to decode the incoming signal using say DPLII to provide surround sound.