I am using a y-splitter to play audio from my laptop/ipod. I am using a Harman Kardon HK 3490 receiver. I seem to get the best sound from the "Main In" audio input. However, I was under the impression that I should plug this cord into a "CD In" or "Tape In" jack. But again, I get the best sound from the "Main In" input. Sound is barely audible through the "CD In" or "Tape In" inputs. Is the "Main In" the right input?