So I am looking at two units; JVC KD-HDR70 or JVC Arsenal KD-AHD79, both are identical except for the preamp voltage. Arsenal has 5volts and other unit has 2.5volts. Only a $10 difference for the Arsenal unit, which I will prob go with. Is there a noticable difference with going with the higher voltage or not really? Only will be running a mono amp (Boston Acoustics 400m).