Question for any onwers of Fender Bassman 25s: I just got a brand new one in the mail today, primarily so I can play bass upstairs when my toddler is sleeping. I plugged in the headphones and turned it on, and while sound came through the headphones, it also still came out of the internal speaker!!! The only way I could get the internal speaker to shut off was to plug in a cable into the external speaker jack. Is this normal? Did I get a faulty unit? According to the manual, the headphone jack should disable the speaker. I wonder what the effects of having an unconnected cable plugged into the external speaker jack are.