Not an equaliser, but a mixer.

It is essential, in my opinion, if you have multiple computers, and or multiple midi modules or other external inputs.

Yes, you could daisy chain much of that stuff, but that's begging for trouble and far more complex than being able to immediately mute/pan/boost a given channel or device.

Yes i have of course a mixer (Roland ED M-10).
But some people do have an equalizer too.

Look at this dude https://www.youtube.com/watch?v=bQn3SyDh2Xo
He has an equalizer under all his MIDI devices.

I've thought about building an audio rack for use with my retro PCs. In part, because I tend to use multiple sound cards so having rack mixer + EQ and other hardware could be interesting.

On the flipside, there are a lot of physical space, cabling, and power requirements when you start getting into setting up something like that.

The best option would be doing that with something like a music studio desk with build-in rackmount capabilities.

As far as equalizers go, the EQ is very important, I would say even essential since it allows you to make things sound just right or very least less shit (depending on exactly what kind of speakers or headphones are at hand). You won't be able to get nice bass out of some small things or proper highs from something without tweeters but it is still possible to shape the sound much closer to ideal with an EQ, or simply cater to your personal preferences. I have a 10 band EQ in my computer setup, right next to the amplifier for the speakers.

Tiido, care to share what equalizer you are using? Also interested to see what kind of speakers you are using.

The devices are soviet era things, simply because they were affordable where I used to live (Estonia) and have known and often excellent performance.
Equalizer is Elektronika E002 (that I use with Pioneer SA-420 amp) and speakers are Vega 25AS-101. I actually have two of these EQs that I bought years ago for just 8EUR, neither worked and one isn't complete but I could make one complete and working one out of the two and the other one I will turn into a 20 input mixer once I get some PCBs ordered. With that I will have the computer desk sound side completely taken care of but there's some more time until I get to that point (as one can see, the speakers aren't even at the desk right now 🤣).