you should be fine as arch are compiling their binary with alsa enabled https://git.archlinux.org/svntogit/packages.git/tree/trunk/PKGBUILD?h=packages/firefox

you should be fine as arch are compiling their binary with alsa enabled https://git.archlinux.org/svntogit/packages.git/tree/trunk/PKGBUILD?h=packages/firefox https://git.archlinux.org/svntogit/packages.git/tree/trunk/P... line 97 for reference