Hello, my name is Rusty. I'm a sound engineer, I can help you. The outputs are a line level, so the preamp is definitely too much. You have a couple of options.
Best sound option:
Click here. The black knobs at the top on channel 1 and 2 are variable preamps designed by Midas, so they sound great. You can dial in the audio with one of these mixers with the preamp so the levels are in the yellow, and raise the volume until it peaks between -6 and -1 in Audacity.
Record the songs into Audacity as is. When you're done, double click the waveform to highlight the entire thing. Click the Effect menu, and select Normalize. Set it to maximum output of -1db, and click OK. Normalize will amplify it until it's just below clipping, but will keep the dynamics of the music.
Let me know if you have any questions.