Hm. I am going to have to test this, but it might be due to unconditioned power? My house has very bad power and alot of things can easily generate static. I have a power conditioner running for all my equipment, which results in things being quiet.
Also, there can be an issue with a ground-loop as a result of something interesting with the cables, or even a fault power supply cable you received with the da100. If you have an alternate power supply cable you could try, I highly suggest that.
Lastly..nothing stops you from grounding the chassis of the Stello or your other equipment to a chassis of something you know has it working well. Just need a piece of wire =]
Check for external interference also, objects such as screens can occasionally have such influences.