ipod w/o a receiver? & resistor questions

question for all you ipod users. are you able to adjust the volume when you run a line out(i.e. rca jacks) i currently use a creative labs and am not able to adjust the volume when i run a line out.
could i just use this plugged into an amp as long as i used a switchable power source to turn the amp on and off?
lastly i have a creative labs mp3 player which operates on 4.3 volts. can i take a plug of higher voltage(for cellphone or whatever) and use a resistor to obtain the desired voltage?? a standard universal plug wont work(too much or to little voltage). later alan

Resistors will not provide a stable voltage source, use a higher current dedicated voltage supply. Try Radio Shack 273-1857 should work.