My favorite late night activity recently: playing with my 16-bit 64 kB fantasy computer that has a SID-inspired but more advanced sound chip. Here's some demo samples, and Yamaha synthesizer clone:
https://fanco16.kissa.dev/v4/chipbook.html
https://fanco16.kissa.dev/v5/synth.html
fanco16.kissa.devSIREN FNC 4032 · Programmer's Reference and Cookbook
commit 5a11915
Currently in iteration v6 of the chipset, trying to reproduce the sound of a Steinway piano - all in Hal of course
https://fanco16.kissa.dev/v6/piano/
fanco16.kissa.devSteinway → SIREN — A4 study