Here are my observations of the Digital Stream DTX9900 vs the Zenith DTT900, both of which I bought about a week ago. Overall I like the operation and features of the DS unit better, but the Zenith has a significantly more sensitive front end in it. For the sensitivity comparison I used the same outside antenna and the same NTSC television receiver. Keep in mind that that this was made by comparing only one of each of these models and there could be individual performance differences amongst different converter boxes. So if I lived in very hot signal area, I would be happier with the DS, but since I live in a slightly marginal reception area, the Zenith is my preference. I would be interested to hear if others have done side by side comparisons.