Is it possible to test the pre-out for the sub. I have a CDA-9833 which
supposedly has 4v pre-out, however Alpine customer support have told me to
set my amp imput to be 0.1-1v after I had problems getting my amp and sub
working at a volume above a wisper. Although my sub seems to be working ok
now, this does not make sense to me, could it be that the head unit is not
outputing the correct voltage?

Gav