well it could be for a few difrent resons that your having this problem. for one where do your loops come from do you record them yourself or do you use loops from someone else? if you make the loops it could be in your recording. are you monitering the sound source and then the sampled loop on the computer from the same source?

another thing to do and dyeone sorta mentiond it and that to cut unused frequencies. so on the drum line use a high pass filter and cut out some of the lowest frequencies and do the opisite on the bass line, send it through a lowpass filter and to take out some of the unecasary high ends(this will usually phaten up the bass line as well) the basic idea is to not let frequencyes from difrent loops interfear with another one, if there are to many frequencies that are the same you get a muddy muffld sound thats not pleasing or profesional sounding. work with the eqs alot it takes time to get it right. just remember you want each sample to be using sorta its owen frequency.

Compresion shouldn't help to much in this case unless you are getting a muffled sound from having your bassline way louder then beat loop. if so you could try eqing more bass into the bass line and compressing it to make it louder (you loose some of the dymaics when you do this) you should then be able to turn your bassline down and it will still sound higher and may inprove this muffled sound your getting.

anyways one or all of these may help you, good luck

Dj Taos