Ubuntu – Volume too low on Ubuntu 17.10

I've a 2.1 sound system and on a Windows PC it works very well. On Ubuntu 17.10 and 16.04 the volume is lower than Windows also at 100%. I've already tried looking at alsamixer (a mixer program for the Advanced Linux Sound Architecture) and it's OK, all at 100%, if I increase max volume over 100% it's sounds very bad. I've also tried to reinstall alsamixer and PulseAudio (a network-capable sound server program) but nothing to do.

Here is the output of this long set of commands:

cat /proc/asound/{version,cards,devices,hwdep,pcm,seq/clients}
ls -l /usr/share/pulseaudio/alsa-mixer/paths/
sudo rm /etc/asound.conf
sudo rm -r ~/.pulse ~/.asound*
sudo rm ~/.pulse-cookie
sudo apt-get update
sudo apt-get install aptitude
sudo aptitude install paman gnome-alsamixer libasound2-plugins padevchooser libsdl1.2debian-pulseaudio
sudo lshw -short
ls -lart /dev/snd
find /lib/modules/`uname -r` | grep snd
cat /dev/sndstat
lspci -nn
lsusb
sudo which alsactl
sudo fuser -v /dev/dsp /dev/snd/*
dpkg -S bin/slmodemd
dmesg | egrep 'EMU|probe|emu|ALSA|alsa|ac97|udi|snd|ound|irmware'
sudo /etc/init.d/sl-modem-daemon status
sudo grep model /etc/modprobe.d/*
sudo dmidecode | egrep 'anufact|roduct|erial|elease'
lsmod | egrep 'snd|usb|midi|udio'
pacmd list-sinks
aplay -l
sudo alsa force-reload
ubuntu-support-status
sudo lshw -C sound

Output on Text Share or
Pastebin.

My notebook: Dell Inspiron 7559

Audio codec: Realtek ALC3246

What can I do?