Watage/voltage on head unit
#2
the watts is how much power per speaker it is putting out. most are around 20-30rms and 50-60 max. the voltage on the other hand has to do with the rca preouts in the back of the hu. they range from 2volts to 8volts. more volts = better singnal. if you do get a smaller voltage hu you can get a line drive to make the signal stronger