When you are talking about frequencies above audio the cable characteristics start to
become more important and we have to start using transmission line techniques. Every cable
has a characteristic impedance which is a function of its capacitance and inductance and
each end of the cable must be terminated with a matching network (often just a resistor
but it can be more complex) in order to prevent reflections from the ends corrupting the
So the reason for terminators is exactly the same for SCSI as it is for
AES/EBU or SPDIF although the value of the resistors may be different.
PS - if you've ever looked at the utilities that come with some computer network
adaptors, you will often find a cable length tester. This uses the fact that an
unterminated cable will reflect a pulse back and measures the time taken for the pulse to
return to give the cable length.
JRP Music - Audio Mastering and Restoration.