alsa-tools-gui software package provides GUI based ALSA utilities for specific hardware, you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install alsa-tools-gui
alsa-tools-gui is installed in your system.
Make ensure the alsa-tools-gui package were installed using the commands given below,
$ sudo dpkg-query -l | grep alsa-tools-gui *
You will get with alsa-tools-gui package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | Sound |
| Package | alsa-tools-gui |
| Version | 1.1.0-2 |
| Description | GUI based ALSA utilities for specific hardware |
| Sub Section | Sound |