I know some audio interfaces and mixers don't have pads to attenuate the signal if its too hot. Its frustrating if you have your gain all the way down but the signal is still clipping! Years ago when I first started doing live sound I made a few pads for old mixers without pads and they never failed me.

Pin 1 (Ground/ earth):
Pin 2 : Solder one 10Kohm resistor (preferably at female end)
Pin 3: Solder one 10Kohm resistor (preferably at female end)
Pins 2 & 3: solder 1Kohm resistor (preferably at male end)
This is a design I took from Duncan Fry's Live Sound Mixing book which is pretty much the idiots guide to audio.
There are probably better pad designs out there but this one worked for me. Manufacturers charge ridiculous prices
for pads however you can make your own for a couple bucks.
Keep in mind that many cheap interfaces use pads instead of a dedicated line input. So even though the button says "line" it may just a pad.