It costs nothing to lay the phone down someplace other than the amp you're playing on. Fixing bad house wiring costs a lot more. It's the wireless on the phone. Nothing more. Nothing less. If my phone is on top of my guitar amp, there's noise. If I lay it down on my bass amp right next to my guitar amp, no noise. If I'm playing the bass amp, noise. If I move the phone to the guitar amp, no noise. It's less than a foot difference. I use my phone for practice almost every day. Even if I'm not using it, I still lay it down in the same spot - on the amp next to the amp I'm using.