Apple Performa 6400/180 - Manual (Page 68)

Specifications I/O Interfaces - 14
Sound Output 16-bit stereo output featuring SRS 3D Surround Sound
technology
One 3.5 mm sound output port for line-level devices, such as
powered loudspeakers, on the back of the computer
One 3.5 mm headphone jack on the front of the computer
Sound Input
16-bit stereo input
Sample rates of 11.025, 22.05, and 44.1 KHz
One 3.5 mm sound input port for stereo sound input. Supports the
Apple PlainTalk Microphone that comes with some Macintosh
computers, as well as non-Apple microphones. Also supports a
standard stereo (miniplug-to-RCA) cable adapter for
connecting stereo equipment to the computer.
Note:
Does
not
support the Apple Omni microphone (the round
microphone shipped with some earlier Macintosh models) or
the attenuated RCA adapter provided with some models.