Arduino potentiometer (external power) with amplifier i am trying to make some kind of an amplifier. I got an amp board but want to read out the value from the potentiometer. The problem is that this pot is connected to the amp and has to be connected to the amps power Is there any way i can still read data (with an arduino) so that i can have a volume percentage on a lcd? Or is this imposible?

Amp 24v Potentiometer = 6pin. B50k

also what zould happen if i connect a 10k resistor instead of a 50k ressistor (audio potentiometer) what would the effect be?
It's impossible. The pot is most probably acting as a passive variable attenuator. As such the top end will be the incoming audio signal, the lower end will be ground, and the wiper will be the attenuated incoming signal. There's not a lot you can do with that.  

You would need to replace the pot with an equivalent triple pot (if such a thing exists) and have one third of it connected to the Arduino.  The pot you have at the moment is a dual pot, and a log taper at that.

Alternatively adding some kind of quadrature (motor) encoder to the shaft of the pot may be a possibility.