Low output level from audio devices
Many people have noticed this problem, but I have actual measurements that illustrate it. For measurement, I used Audacity running on a Windows computer. For the connection from the audio source to the measurement box, I used a stereo splitter with a cable to the Windows audio input. I used three source computers, Intel and AMD systems and the Windows system. On the first two, I generated audio with both audioplay and firefox. On each source, I also had speakers connected to the splitter as well, so I could hear the sound.
In Audacity, I had the input slider set at 0.5 . I enabled monitoring, and noted the peak input level on the input meter.
With audioplay, I ran rooster.au in a loop until I got the measurement I needed. Audioplay sends the audio directly to the audio device. Pulseaudio is not involved.
With firefox, I played the same youtube song on each source computer. I assume that Pulseaudio is involved in this test.
The Intel computer used an ASUS PRIME B360M-A motherboard with an Intel(r) Core(tm) i3-9100 CPU and ran OI. It used the audiohd driver. The audio output slider was at 94%. With both audioplay and firefox, the output level was -24 db. I'd call this audio level low but acceptagle.
The AMD computer used an ASUS PRIME B350M-A motherboard with an AMD Ryzen 3 1200 CPU. It also ran OI and also used the audiohd driver. The audio output slider was at 93%. With both audioplay and firefox, the output level was -33 db. I'd call this audio level faint and unacceptable.
The Windows computer was an HP 8000 Elite SFF machine with an Intel Core2 Duo E8500 CPU and ran Windows 10. The audio output slider was at 98%. With firefox, the output level was -6 db. I'd call this audio level loud.
I conclude that the driver or the hardware is responsible for the low volume, since audioplay and firefox produce the same output level. People usually blame pulseaudio for the low volume, but this seems not to be the case. I also conclude that the volume on AMD is lower than on Intel, by 9 db and that the volume on both OI machines is lower than on Windows, by 15 and 24 db respectively.
Updated by Gary Mills 3 months ago
The AMD computer has two audio devices and two mixers. In my audio level tests, pulseaudio was using the correct audio device but the wrong mixer. When I fixed this problem in pulseaudio, the audio level increased to become similar to the Intel computer. With my firefox test, the audio level was -25 db. I'd call this level low but acceptable.
That result again implicates the device driver as the software responsible for the low audio level.