Combining electrically the signals from microphones, tape, and reproducers and other sources.
"I recently had an old 8 track cassette copied to a CD - it was actually the soundtrack from my wedding ceremony from 8/31/74. This is just to say Thank You and Great Job! I really thought it was a lost cause but my son persevered with his internet search and found your company. The quality of the sound is amazing for what you had to work ..."