I'm thinking: are you taking about taking a garageband sound and loading it into Logic (one based on samples and opens EXS)? If so, try this: drag the loop onto a blank part of the arrange window. That will make the correct channel strip sounds (effects, etc) load.
It doesn't always sound 100% the same, but it's allot closer than just trying to load the EXS without the FX.
I have these .wav files that I bought and I am trying to use them to create EXS24 instruments. I drag the .wav file from my iMac finder window in to EXS24 sampler and the sound is different. I am previewing the sound using the eye in the finder window.
Here id an important thing to know: when you play a sound using the "eye" or selecting and then hitting your space bar, the sound is being played full system volume. When you play a sample vix EXS, t is being played at a different volume, usually a few DB lower or more. So the difference in the sound is likely to be a volume difference rather than a tonal difference, as long as you don't have any filters engaged in EXS.