Yikes. I make sure my dehumidifier, all dimmers, the soldering iron, the projector and the treadmill are off before a session. I can't imagine a transmitter being that close to a tube phono preamp. Heck, even my CD/PC are in another rig. I can hear a difference if there is a CD player plugged into my preamp! I see you do not have a turntable so it may not impact you as much. But yeah, get the audio on its own power circuit and move the router as far away as you can.
Tweak or Tin Foil Hat?
I have noticed that my tube amplifier has some noise in it on occasion that seems to be related to my AirPort Extreme wireless router that is in the the same cabinet in the adjacent space. If I get serious about my listening and my wife isn't home I will unplug it, but I have been thinking about using tin foil to make a barrier lining in the cabinet. Any reason to think this might make a difference? I just have not had the time when I think about it to give it a try as of yet.