On my HP laptop (which I'm using as a desktop, with an external HDMI monitor) it, by default, seems to want to send sound to the HDMI monitor which, alas, has no speakers. To get sound to come out via the headphone jack (and hence to an external speaker) I had to
blacklist snd_hda_intel
then, in onboot.lst load alsa-config.tcz and alsa.tcz (in that order) and then, in bootsync.sh, run
modprobe snd_hda_intel options index=1
I don't know if, in my case, it's dependent upon Xorg-7.7 and graphics-KERNEL because I pretty much always have those loaded anyway.
I also load apulse.tcz and use apulse to run firefox. Otherwise, no sound in firefox.
Of course, your hardware configuration is likely much different than mine. And if you use that USB stick in multiple machines, it may also vary from one usage to the next.