question, which system do you have? I wasn't able to get this to work on my E1505. for now I have no mute of speakers when headphones are plugged in. Ultimately, the goal is to get this to work on the latest system though.
I also have an E1505. Booting Leopard from a portable HDD.
I also used the taruga technique for sound way back, and had the sound with no mute during headphones.
I don't really know how to help out, though I do get random crashes on boot, and just now i got this error.
sound assertion "0 == entry failed in "AppleHDA/AppleHDAEngine.cpp" at line 2363 sound assertion "0 == entry failed in "AppleHDA/AppleHDAEngine.cpp" at line 2396
then it just repeated the 2nd line for awhile and stopped and froze
maybe thats a lead, or maybe its just my install.
also i have an idea. don't know if its related at all, but there is a kext on kalyway for Intel VIA NVIDA ATI HD Audio or somemthing like that, and since sound is detected as Intel High Definition Audio, i am wondering if installing said kext would help get sound through speakers???