I have had Tinnitus since I was 15. Its really very annoying and of course very easy for me to judge subjectively as I can hear it. I will know unequivocally if TDCs has worked or not in this case.
Unfortunately TDCs does not offer a 100% cure for tinnitus.
I need to spend 2-3 days studying the research papers before I decide upon the electrode placements.
Also thanks to http://www.diytdcs.com for linking to this blog. They have quite a good blog with general information on TDCs. You also will come across www.mindalive.com who sell light and sound devices and have many links to research on TDCs.
You may also come across the goflow device - seriously do you need to shell out $100 when a TDCs device has two resistors and a regulator ?
If you really must buy a device you may as well go the whole hog and get a medical device.