B Feelgood

I am installing a few accessories into a an SL55 and need help locating a power source. The accessories are an audio equalizer, bluetooth adapter/module, and a phone charger. I've installed this setup in a few other cars in the past and I've always spliced into the cigarette lighter power wire. This gave me the switched power that I needed but with one problem. This power source introduces a ground loop hum (high pitch squeal in speakers that varies upon RPM) that requires a ground loop isolator to fix. The isolator does indeed fix the ground loop but it also degrades the sound quality (even tried the expensive Jensen CI-2RR). I've read that it's usually a bad ground that can introduce a ground loop but I've tried grounding these accessories in probably 5 different places (including factory location where all audio grounds are at) with the same outcome.

I'm not sure why but it seems like the cigarette power wire seems to introduce this noise. Therefore, I'm looking for for another place to tap into for power when the key is in position 1/2. I've tried the power wires for the two antennas going into the stock head unit but they didn't supply enough juice to power the new accessories. I know that the phone charger uses 2.4 amps max but not sure about the equalizer/BT. I know that they are both low power draw devices though.

Are there any fuses behind the passenger seat (rear SAM) that I can use a fuse tap with to get the power needed? I thought that I remembered reading somewhere that all of the "switched ignition" fuses are under the hood on the driver's side SAM but I could be wrong.