These are the packages that would be merged, in order:

Calculating dependencies ... done!
Dependency resolution took 1.29 s (backtrack: 0/20).

[ebuild  N     ] media-libs/libogg-1.3.6::gentoo  USE="-static-libs" 430 KiB
[ebuild  N     ] dev-build/bmake-20260912::gentoo  USE="-test" LUA_SINGLE_TARGET="lua5-1 -lua5-3 -lua5-4 -luajit" 990 KiB
[ebuild  N     ] media-libs/alsa-topology-conf-1.2.5.1-r1::gentoo  USE="-verify-sig" 12 KiB
[ebuild  N     ] media-libs/alsa-ucm-conf-1.2.16.1::gentoo  USE="-verify-sig" 83 KiB
[ebuild  N     ] media-libs/alsa-lib-1.2.16.1::gentoo  USE="python -debug -doc -verify-sig" PYTHON_SINGLE_TARGET="python3_14 -python3_12 -python3_13 (-python3_15)" 1104 KiB
[ebuild  N     ] dev-libs/libatomic_ops-7.10.0::gentoo  531 KiB
[ebuild  N     ] net-libs/libasyncns-0.8-r5::gentoo  USE="-debug -doc" 334 KiB
[ebuild  N     ] media-libs/opus-1.6.1::gentoo  USE="-custom-modes -debug -deep-plc -doc -dred -hardened -osce -static-libs -test" CPU_FLAGS_X86="sse" 10228 KiB
[ebuild  N     ] app-eselect/eselect-mpg123-0.1-r1::gentoo  0 KiB
[ebuild  N     ] dev-lang/orc-0.4.42::gentoo  USE="-static-libs -test" 275 KiB
[ebuild  N     ] dev-cpp/abseil-cpp-20260107.1:0/2601.1.0-cpp20::gentoo  USE="-debug -test -test-helpers" 2251 KiB
[ebuild  N     ] app-text/lowdown-3.2.1:0/4::gentoo  767 KiB
[ebuild  N     ] media-libs/flac-1.5.0:0/11-14::gentoo  USE="cxx -debug -ogg -static-libs" CPU_FLAGS_X86="avx avx2" 1054 KiB
[ebuild  N     ] media-libs/libvorbis-1.3.7-r2::gentoo  USE="-static-libs -test" 1176 KiB
[ebuild  N     ] media-sound/lame-3.100-r3::gentoo  USE="frontend -debug -mp3rtp -sndfile -static-libs" CPU_FLAGS_X86="(-mmx)" 1489 KiB
[ebuild  N     ] media-sound/mpg123-base-1.33.7::gentoo  USE="alsa ipv6 (-coreaudio) -int-quality -jack -nas -oss -portaudio -pulseaudio -sdl -verify-sig" CPU_FLAGS_X86="sse (-3dnow) (-3dnowext) (-mmx)" 1100 KiB
[ebuild  N     ] media-libs/speexdsp-1.2.1::gentoo  CPU_FLAGS_X86="sse sse2" 901 KiB
[ebuild  N     ] media-libs/webrtc-audio-processing-1.3-r5:1::gentoo  641 KiB
[ebuild  N     ] x11-libs/libXtst-1.2.5::gentoo  USE="-doc" 285 KiB
[ebuild  N     ] media-libs/libsndfile-1.2.2-r2::gentoo  USE="alsa sqlite -minimal -test" 714 KiB
[ebuild  N     ] media-libs/libpulse-17.0::gentoo  USE="X asyncns dbus glib -doc -gtk (-selinux) (-systemd) -test -valgrind" 1530 KiB
[ebuild  N     ] media-sound/pulseaudio-daemon-17.0-r2::gentoo  USE="X alsa alsa-plugin asyncns dbus gdbm glib orc ssl udev webrtc-aec zeroconf -aptx -bluetooth -elogind -equalizer -fftw -gstreamer -jack -ldac -lirc -ofono-headset (-oss) (-selinux) -sox (-system-wide) (-systemd) -tcpd -test -valgrind" 0 KiB
[ebuild  N     ] media-plugins/alsa-plugins-1.2.12::gentoo  USE="mix pulseaudio usb_stream -arcam_av -debug -ffmpeg -jack -libsamplerate -oss -speex -verify-sig" 400 KiB
[ebuild  N     ] media-sound/ncpamixer-1.3.8::gentoo  USE="man unicode" 24 KiB

Total: 24 packages (24 new), Size of downloads: 26311 KiB

The following USE changes are necessary to proceed:
 (see "package.use" in the portage(5) man page for more details)
# required by media-sound/pulseaudio-daemon-17.0-r2::gentoo[alsa-plugin,alsa]
# required by media-libs/libpulse-17.0::gentoo
# required by media-sound/ncpamixer-1.3.8::gentoo
# required by =media-sound/ncpamixer-1.3.8 (argument)
>=media-plugins/alsa-plugins-1.2.12 pulseaudio