I finally got the high pitched noise fixed after doing some troubleshooting..
Grounding the RCA's didn't do anything, grounding the amp better didn't do anything, and turning the gain down didn't do anything. Switched the RCA's with the other pair I had wired for the sub when it goes in, and the noise went away. Must just be a bad pair of RCA cables..
I also tuned the amp more precisely after that.
I complained about the noise to the site (also the decrease in bass over just my headunit) that I bought the amp from and they told me I must have a defective unit. I was thinking about exchanging it for this Hifonics amplifier if they allow me: Hifonics GLX100.4 400W RMS, Class A/B 4-Channel Gladiator Series Amp It is CEA2006 compliant unlike the one I have, and has a higher RMS rating for bridged which I would do for the sub. What do you think?
