Pioneer (now AlphaTheta) issued its final driver update for the DDJ-S1 in 2017. That driver was designed for Windows 7/8 and macOS Sierra. Fast forward to 2024, and most users are running Windows 11 or macOS Ventura/Sonoma. Plug in your DDJ-S1 today, and you will likely get an "Unknown USB Device" error or a frozen audio engine.
Since Pioneer's firmware updater for Mac is a 32-bit application (which modern macOS won't run), many DJs use a Windows machine to perform the firmware update once; after that, the controller will work perfectly when plugged back into a modern Mac. Pioneer DJ DDJ-S1 Quickstart Guide - Serato Support pioneer ddj s1 driver new
Once the driver is installed and the computer is restarted: Pioneer (now AlphaTheta) issued its final driver update