"Line In" requirements

[autir]

In a "typical" (if such a thing exists) Line-in interface

-> What is the input impedance ?
-> What is the Vp-p(max) ?
-> Do PC Soundcards' specifications differ?

Thank you.

 

[audioguru2]

In a "typical" (if such a thing exists) Line-in interface

-> What is the input impedance ?

About 10k ohms.

-> What is the Vp-p(max) ?

100mV to 300mV RMS averaged but peaks could be as high as 11V p-p or more.

-> Do PC Soundcards' specifications differ?

Yes, they are all different, there isn't a standard.
The circuit probably has adjustable gain or an adjustable attenuator. ;D