So, I got to finally jam with my new Bag End S15D-X and it sounded great, while jamming. As soon as we stopped, (coincidentally when a light turned on) I heard a distinct radio-like hiss coming from my new cabinet. The sound didn't last long and came and went a couple times before it stopped. I tried to get it to do it again by playing fairly hard but it wouldn't happen. Later, my cell phone rang (which was on top of the head) and again, a couple hisses. Does anyone know what this could be? As a note, my previous cabinet was a Peavey 410TXF and I didn't have the tweeter on at all. My new S15D-X has a coax turned on at all times. I'm assuming this could be a shielding issue or a cable problem that I've just never noticed before? Any thoughts? Thanks.