Keyboard Impedance?

I just was reading a post somebody had posted about hooking a guitar up to the mpc 1000 which I was also wanting to do and read that a DI box is needed for it, just curious I have a Alesis Micron and do I need a DI box. I mean I was using my micron last night on my mpc and just hooked it up through the left input. Sounded fine to me but just curious if I needed one for that but now after reading that post I plan on buying one for my guitar. Just curious, how do you know when you need to use one?

You don't need a DI box for any relatively modern keyboard. Unless you wanna run your keys or samples thru a mic preamp to 'warm them up'.

how do you know when you need to use one?

when you need to match impedance and signal levels between devices. for example, hooking a giutar up to your MPC,

Guitar = low level, high impedance,
Line level inputs/outputs like keys and samplers = high level, low impedance,
Mic inputs = low level, low impedance

http://www.soundonsound.com/sos/jun02/a ... iboxes.asp