I'd suggest following the request from ame, above. Just to verify that the *Pi* is working correctly.I assure you a standard installation of headless plexamp on a Pi4 results in a 7.1 signal without center channel being sent out.
I don't, off hand, know of anyone else who is trying to use HDMI (a *video* plus audio) standard to output just audio. To the best of my knowledge, the standard does include some "handshaking" between source and sink. Does your audio system include provisions for such handshaking, or does it simply assume that it is going to get some (unspecified) audio format that is used for the HDMI audio channel(s)?This is ridiculous that I find an obvious problem with the product, and instead of troubleshooting it, people want to pretend all is fine.
I don't do much HDMI audio out, and when I do, it is through speakers embedded in a monitor. That has worked with no issues. So other than testing with a "typical" setup--as suggested by ame--to verify that there isn't anything wrong on the Pi end, you may have to dig very deep into Pi documentation to see what options are available and may be needed and do the same for your attached audio device to verify that it is set up correctly.
Statistics: Posted by W. H. Heydt — Mon Jun 16, 2025 11:42 pm