Opto-to-coaxial audio converter:

Most audio equipment produced in the past five to ten years has digital inputs and outputs. It is a pity, though, that there are two standards: optical and coaxial, and not all equipment has both. Fortunately, the connection difficulties that may ensue are easily resolved by the use of the adaptor described in this article. This enables any optical output to be converted into a coaxial one or vice versa.