I just realised that 1 of my 2 1spots hum. It's a weird hum cos the hum is always there on the amp, even when the volume is at minimum. The volume of the hum does not increase with the volume knob. Same when I plug my board to the line in of my sound card, except that the hum is louder. Anyone else experiencing this? It doesn't seem like I can open it, there's no screw, if not I can try fixing it myself..