I once saw a C64 disk drive 1541 play the US national anthem by moving the floppy drive head across the disk in patterns to produce mechanical noise which vould be interpreted as a melody/tune. So a combination of a cheap built in speaker and a floppy disk could have produced stereo sound!!!!

Meanwhile, 8 year old Amigas were playing 12 bit digital stereo sound on 4 channels … on a preemptive multitasking system on a machine with less RAM and a < 8Mhz CPU.