We had a mini CD adaptor in the house when I was a child (basically a plastic ring with clips in the cutout so it'd hold a mini CD and make it the same size as a regular CD), but everything that took CDs that we owned had an indentation for a mini CD already or had you put the disk on the spindle yourself. The two exceptions were later on, a Nintendo Wii, which would have worked as it played Gamecube disks and they were the same size, and a slot-loading car stereo, but we didn't have any audio mini CDs, so I've no idea if that would have worked better or worse with the adapter.