You can hear how DaDMaN's interface sounds here: [https://soundcloud.com/david-donaire-s-nchez/sets/amstrad-cpc-sonique-sound/ Playlist on SoundCloud]
According to [https://patents.google.com/patent/US4677890A/en Google patients patents for US4677890A], the patent for the SID chip is now expired.
*[https://youtu.be/yadWu7hs4MU Oscilloscope comparison of 4 different SID chips]