Ripping LPs to Hard Drive

I'm want to use Audacity to rip my records to hard drive, but I have a problem. The signal input level is too low. I have the "gain" slider in the Audacity program maxed out, and the gain level on the line input of my sound card is maxed as well. I was hoping to get signal levels to about -6db but the meters are topping out at about -24db. What can I do to give the input a bump?