Can I change sensitivity of line input level? (as opposed to setting the volume) I'm connecting a standard stereo tape output to an iMac line input socket. Setting input level in System Preferences > Sound > Input > Line In requires the slider to be barely "off the stop" before the blue level meter hits hard right.  Can I lower the line input sensitivity somehow?  There's no output level control on the tape output.

I'm running Mountain Lion.
Have you tried using LineIn by Rogue Amoeba?