Serial Copy Management System (SCMS)

Due to music industry (and political) pressure, Sony added a copy protection system, SCMS, to the MiniDisc format. This system sent a signal via SPDIF (digital optical and coaxial audio) to ask the receiving equipment not to allow recordings. This effectively blocked 2nd generation (MiniDisc to MiniDisc) copying via lossless digital connections. Although less relevant today than in the 1990s, SCMS can still pose a challenge to modern MD users.

When copying a MiniDisc's content to a PC, you may wish to use a digital connection to preserve the MD in its purest form. Unfortunately, the most common USB audio device with digital input (as of 2021), the Cmedia CM6206, accepts the SCMS signal and entirely blocks digital input carrying it.