I dont have any experience in setting gains as I have always got someone else to do it for me, but this time I thought i give it a try. Read a few guides and yutube videos - particularly one where the guy creates a tone on Audacity - plays it through the HU - and adjusts via multimeter whilst setting the gain.
I tried to do that but when I got into the car i failed at first hurdle as I could not see what volume i was at. So I set it as high as I thought was safe and unplugged all speaker/sub connectons from the amp. I played the 60 hz tone through and conencted the multimeter but I did not get any readings, it stayed at zero (I had the multimeter set as per in the youtube video)
i then played a normal bassy track and mid volume and the reading was fluctuating all over the place - I dont know what I am doing wrong