
If you get a mixer with USB or Firewire from Mackie, Alesis, or M-Audio, then any audio inpute go straight into your musical sequencer like Live!, Cubase, Cakewalk, Pro Tools, etc. (Not Reason, since they don't support this feature). If you buy a mixer without a direct input into your computer, fear not. You will just need some sort of breakout box or some rackmount device that will do the same job. If you had to go that route for some reason, get one that supports as many audio ins/outs as you can. Think of it like this, if you bought a keyboard, and your buddy brought his guitar, and his sister brought her bass, how would you go about mixing the beats of your mpc1k, with all the other instruments? This is why a mixer is soooooo essential when you have more than 1 instrument. Most people think they dont need one, but they find it extremely difficult to do everything like mix in mic pres, boost/cut frequencies, and mix more than one instrument in real time without spending more money. The mixer isn't going to alter your sound too much (just shaping high, mid and low freqs), but if the mixer has any built in effects, then it might to a degree. But more than likely your mixer will accept any compressor or effect processor you buy in the future for it.