Looks like a very basic single-band compressor. Should suffice for its intended purpose of keep rather constant volume. The input side allows for tweaking to tailor dynamics, but dynamic compression and eventual hard clipping can (and likely will) become an issue if driving the circuit hard enough.
The thing with music is the potential for huge variations across the audio spectrum. A multi-band compressor and/or clipper to separate out lows, mids, and highs into various bands with their own characteristics tends to be preferable for the commercial "broadcast" sound; assuming one is looking for that type of sound.
If you want a mostly point-and-click software solution, the JB Broadcast VST plugin used to be popular for streaming, local low-power broadcasting, etc. It has a few presets that tend to work decent for many situations.
I prefer StereoTool for my local audio processing. There are lots of presets, but many require extra paid features for optimum sound. Deeper configuration can get into hundreds of settings if really determined to fine tune a custom sound profile. One can easily spend hours tweaking various settings if desired. Been there, done that.... and what I find sounds good another might find to sound horrid. So YMMV of course.
Admittedly I use ST largely for declipping and restoring some dynamics, which tends to be the opposite of commercial broadcasting. ;)
Topic: Inexpensive Automatic Volume Control for Part 15 stations? And, other things. (Read 1122 times)
