Good news--thanks for the followup. The reason I asked about the red glow is that the audio-out port on later PowerBooks is digital and held to higher dimensional standards than many analog stereo mini-plugs use. If the tip-to-shoulder distance on a device's plug is too long, it jams the port in the "mute' position and a red light comes on in the port. Most people don't get away with the simple PRAM zap that helped you, so you did well in solving the problem.
To give an idea of how much the dimensions on analog plugs vary, here is a picture of my first MacBook Pro with the plug for a respected, name-brand set of headphones attached:
In spite of bing quality headphones, the tip-to-shoulder distance for the plug is too long and, as pictured, is fully engaged with the proper contacts, but the shoulder of the plug is about 1/8 inch from being fully seated. If I inserted the plug farther than shown, it would jam the contacts.
What I had to do with that computer and headphones was to open the sound source first, then slowly insert the plug until I heard proper stereo separation in the 'phones. At that point I stopped pushing on the plug. A bit of irony is that a no-name set of external speakers I picked up at a garage sale for US$2 has a plug that fit the old MBP perfectly. Go figure!