Many Android users may be aware of the JamesDSP audio processing system. So here it is implemented as a plugin for good old Linux ALSA without any intermediate frameworks like Pulsaudio or Pipewire.
I know there are ports of JamesDSP for Pulsaudio and Pipewire (Audio4Linux project). So what's the rationale for this one you ask? I have a DIY smart speaker system (https://github.com/faust93/RIVA-Festival-DIY-Info) built around ARM single-board computer (NanoPi NEO) and I need a system with minimal footprint and all these audio frameworks on top of ALSA such as PulseAudio are simply overkill in that case.
DSP properties can be controlled in real-time using CLI interface or using simple WebUI - https://github.com/faust93/alsa-jamesdsp-gui
So I hope it will be useful for those who use just plain ALSA for whatever reasons. :)
I first saw arvid in action while my dad and I visited his mate to copy some software and games onto floppy disks. That guy had a BBS station that time with files sharing enabled. Some of that files were available for downloading straightaway and some were required 'a pre-order' so he had to recover it from the VHS tape first and then place online as I understood later. Downloading with 2400Bps modem was a torture and my dad said 'hey, I know that guy personally, let's go and grab all the files you need..' Regarding the purchase. At the time I lived in a large industrial city 1000km south of Moscow and there we had several resellers in town (small computer hardware retail firms mostly) not sure if it was official or not. Another purchase option was the so called 'radio market' a weekend event where people met to exchange,sell or buy computer software and hardware parts. So yep, there were no official ads or whatever and mostly it was a 'word of mouth' among techies as you mentioned it.
I was a lucky owner of the ArVid 1030 back in the 90s. Compared to my PC's hdd size that time (WD 500MB) arvid was able to store about 2GB of data and that was an insane amount! Good old days.. :)