I've been having a problem where the volume level of my Dell Studio 17 notebook is just not loud enough when I'm running Linux. I went to windows, to see if the problem was the same there, and I found that the volume in Windows Vista was way higher. So, I booted back into Linux, and started googling.
I quickly found a few places that talked about setting the model to 3stack, and various other options. But, none of that worked for me. So, I decided to search for the problem on my own. I ended up checking out the alsamixer again, from the command line. Last time I checked, I saw that the "Speaker" volume was set to about two thirds, but I had thought that was referring to the volume of the PC Speaker, as on many sound cards, it is actually an option. As it is, that is actually the volume of the external speaker. Once you pump that puppy up to 100% the volume level is good. From there, you can simply adjust the master or PCM volumes as you choose.