Philips VTR5500 Manual page 55

Line in Record：
Line in Recording is a way of recording sound by connecting
the device to an audio equipment's audio output correctly via
stereo audio cable (audio equipments such as radio, CD, VCD,
DVD etc.). Use the stereo audio cable come with the device to
connect the audio equipment's audio output with "Line in" jack
of the device. The recording operation is the same as recording
with microphone. Before recording with Line in jack, please
adjust the volume of the sound source to a suitable level,
otherwise the recorded sound may lack fidelity.
(2) Digital Noise Reduction
When the Digital Noise Reduction function is enabled, the
system can effectively filter the noise from sound source during
recording, and then you can have clear recorded sound. See
55