Hope someone can help~

When I record into Garage Band using an external sound card, I have to turn the master volume output on my Pioneer mixer WAY down (like down to one green line on the meter), otherwise the input levels on the track I am recording in GB go completely into the red. I don't want to get any distortion or clipping in the recording, so it seems like turning the volume down on the mixer is the only option I have - but when the recording is finished, it's really quiet and even muffled sounding, not as clear as the original source. If I burn it to CD, it is much quieter than a normal CD and you have to turn the volume way up, then there is usually hissing in your speakers...

Does anyone have any advice? Should I turn down the decibel level of the track I am recording in GB? I want the resulting recording to be just as clear and loud as the original audio.