Ibanez Gio GRG220PA and Fender Starcaster constantly hum when plugged into either my amp or audio interface. The hum doesn't get better or worse when I touch the strings, unlike what's often reported by other people with their guitars. I note the following:
The hum/noise sounds exactly the same with either guitar.
There is no noise when only the amp or interface + monitors is on without the guitars connected.
I bought a multimeter and tested the ground continuity in the Gio since it's the newer guitar. All seems fine there. I also tested the ground connection in the electrical outlet itself, again with no issues.
I have worked around this issue for months by cutting the noisy frequencies with eq, but that makes my tone sound undesirably muffled
I'm pretty new to both playing guitar and electrical work, so I'm not sure if there's something I'm overlooking. I don't know what to try next. Any help is greatly appreciated!