If you are fortunate enough to have an Ultimate 64 by Gideon, you absolutely MUST play this demo released at the 2019 Evoke competition. It's so amazing to hear 8 SID chips (24 channels) all playing at once! 

In this particular archive there is a .cfg file you can load into your Ultimate 64 that will configure the settings you need to make this work.  If you'd like to preview the demo beforehand, here's a YouTube link.