really from what i know of MPCs, you dont really need one. if you are running cubase then you have everything that an mpc will have. like i said this is from my limited knowledge of mpcs. really if you get a program like native instruments konakt then you will be set as far as tweaking samples. for instance, i took a crash cymbal and turned it into the sound that is in the matrix. you know when neo touched the mirror and the silver metalic liquid stuff goes down his throat? well i got that from just a crash cymbal.
like the guy before me told you, it really depends on what kind of music you are writen. i would suggest the e-mu brand of equipment, they make some good ****. also reason is rewirable to cubase so you could get that and have them talking back and forth to each other. really if you learn about waves and how to alter them, you dont need a lot of equipment, because you can make your own sounds with osc, filters, and so on. i know a lot of people go out and buy buy buy 50 synths because of the different sounds they make. well that is just wasting money if you ask me. you could take one synth, like the cs-80v1 and make almost any sound you want, as far as pads, bass, and so on goes. you have to actually get something for drums that is seperate, if you use drums at all.
do your research, like the other guys said, dont go get it becaue i told you to. everyone does things differently, the end result is all the matters in the long run.
one luv,
joseph n.