In a professional context, XLR is not the same as balanced. I have several pieces of equipment with balanced connections, but only a minority of the balanced c

In a professional context, XLR is not the same as balanced. I have several pieces of equipment with balanced connections, but only a minority of the balanced connections are XLR. Most are TRS. I think you are using a different definition of "noise". "Noise" is unwanted sound. The GSM noise you hear is caused by demodulation of GSM radio, in the 800-900 MHz range. At these frequencies, even a very small wire works well as an antenna. For example, an 8 cm wire makes a quarter-wave antenna. In my experience, there is often a trace of at least 8 cm within an amplifier or monitor which picks up the signal. In these cases, balanced connections do not help. The nonliniarities in semiconductor components then demodulates the GSM signal into the audio band. The worst offenders at picking up GSM interference are cheap amplifiers and radios. Good equipment is well shielded and doesn't suffer from radio interference, and in my experience, using unbalanced connections over short distances (1-2 meters) won't change that. Balanced connections fix ground loops and let you run cables over long distances. That is all. They don't save you from GSM demodulation.