I took my Line6 Spider Valve 212 to the rehearsal studio to do some tweaking at loud volume. I was able to hear the sound of another band practicing in another room COMING OUT OF THE AMP. Particularly the vocals. I am sure that the sound was coming from the amp as it got louder whan I switched to patches with high gain. I checked with the owner of the place who told me that they have no wireless mics (just in case that MIGHT have something to do with this). I tried different a guitar and cables but the problem did not go away. Any ideas regarding what this could be or any solutions to this problem? Thank you.