You can use a pot to attenuate the input (most amps have volume controls that work that way). By the way, www.sound.au.com had a nice article on volume controls, and how to wire a linear pot to achieve a better logarithmic response.
A simple pot in the input is enough in most cases.
22k- 100k ohm is normal.
Most prefered 47 k for standard.
You only need to have a preamp with low output impendance.
If the input has a capacitor for coupling concider putting the cap. before the pot.