Every auto technician or stereo freak should have a good DVM. Radio Shack , Sears, Home Depot... take your pick. Under $25.
An oscilloscope can be had from eBay but if you don't have a clue then you're better off finding a bud who has one and knows how to use it. Too complicated to explain here.
so if i want the proper gain adjustment...i should just take a voltmeter connect it to the speaker wires and match it up with the volt from the sub rca output of the hu?
so if my rca voltage is 2.5v and i set the volume at 3/4 to adjust it...i should juss adjust it to 3/4 of 2.5v???
u don't need the osciliscope if u are not gonna set up a huge system or a comp system. the simple 3/4's volume on cd player with gain turned all the way down then turn up the gain until it starts to distort then back it off about 1/8 of a turn.
i've turned ma amp up quite high on the gain....and couldnt notice any particular sound...it juss stopped getting louder at a point but beyond that...it didnt make any weirder noises