I don't do anything complicated.. all I do is layer em with different sounds.. lets say I don't want to change the original sample too much, I may run it through my emax, but turn the gain up a little. This way, the emax is already gonna add it's dirt, plus the signal is hotter going into the MPC. I use the emax because I got it cheap, but any sampler can do the same thing. You mixing board can do a lot of things, even a cheapo 6 channel behringer with rotary faders.. just turn the gain up from another sampler, and you get a louder sample.
I should also point out that you should always keep the gain down if possible.. the more gain you have, the more hiss you create in your trax. If you can turn your system on and hear the 'hiiiissss', you probably have the gain up too high on some channels, or the output volume is simply up too high. There are other reasons, but I don't want you to buy hum elimiators and other stuff if it's not needed. Actually, I'm going into a whole different subject, so I'll stop now..
ps, if you listen to my track 'old&dirty' the kix/snares are re-sampled the way I described above.
. ..roxstar. ..
http://www.soundclick.com/creamofbeats