[gentoo-user] no sound through headphones (OK through speakers)

[allan gottlieb]

Hardware: Dell Latitude E7450 laptop

Gentoo essentially all stable
Gnome / Systemd

When I play a movie using totem it sounds fine if no headphones are
plugged it.

No sound at all with headphones (I tried three different ones).

The sound settings gui recognizes that headphones are in.  The sound
test is silent.  If I select the internal speakers in the gui (with the
headphones still in) sound is fine.

Is there some headphone option I must enable in the kernel or elsewhere?

thanks in advance.
allan

PS I also tried cat /boot/vmlinux > /dev/audio1.  Silent on headphones