I see that you are running Snow Leopard 10.6.7. Is this the only OS that you have on the Mini 10v? If you are dual booting with (say) Windows 7, just verify that the sound is OK there.
FYI, the sound on my Mini 10v was perfect when I installed 10.6.0 some two and a half years ago and after one of the OS updates (possibly 10.6.4), it became a problem, only working about 50% of the time. During the latter stages of my time on 10.6.7, it had gone completely. Since updating to 10.6.8, it is working flawlessly.
The first time I updated to 10.6.8 (from 10.6.7), the sound was still a bit iffy, so I
1. Re-installed 10.6.0 from the original pen drive that I had prepared (perfect sound afterwards) - this is simple to do, (courtesy of Mechdrew's excellent guides), and if you simply instal on to the existing Snow Leopard partition without re-formatting, then all your files, software, settings, passwords etc etc are retained.
2. Downloaded the 10.6.8 combo update and installed it (you need to grab the Nawcom legacy kernel etc etc for this to work.
Everything on my mini 10v is now working perfectly, apart from the usual greyed out bluetooth on/off which doesn't affect me as I keep bluetooth on all the time to use my bluetooth mouse.
If you would like to try doing as I have done, I can easily point you to the right places to get the legacy kernel and the necessary instructions. The process for doing this procedure are very well documented by some of the good people on this forum.