Actually it can matter, connecting it while it's hot. I'm just being honest, it's a recommended action to disconnect battery power to the amp while making connections to the amp(s) or distribution block, or capacitor(s), and charge them up accordingly. Reason being that connecting it while it has power by the red(positive) wire first can induce a load through the audio cables, even if the amplifier is off, because some amp's internal capacitors must charge to the load and will charge from the closest thing there is to a ground. So always do power before audio cables too. Secondly I wouldn't recommend connecting audio cables if they are anywhere close to another amplifier's power cables, any contact can screw the amp's ground isolation circuitry or the head unit's amp. LOL