New Hard Drive, And Osx 10.4, Loss of External Speaker Output


My old hard drive crashed, and so I had to get a new hard drive and OSx 10.4. My external speakers have lost almost all of their signal. I now have to have them turned all the way up, just to hear a whisper of sound come out of them. I went into preferences and looked around, and the only device i can choose from for sound output is Headphones/built in audio. If the external speakers are unplugged I get sound through the desktop. Any ideas?
Thanks in advance,