Hey all, So I made a rookie mistake and powered on a Tube head without a speaker cab attached to it. Had the amp in standby letting the tubs warm up and turned standby off. Lights went green and then the power to the whole unit shut down instantly. No pops or smoke. Unplugged the amp and realized the cab I thought was plugged into was not any more. Checked the fuse, but I can't tell if it's blow as it's the solid white type and I don't have access to a multimeter. Odds are how much damage have I done to the amp? Could it possibly just be a blown fuse and a lesson learned? Thanks in advance!