Unless I'm mistaken, the DTA box from Comcast just allows you to use a non-digital TV with your cable subscription. You should be able to use any TV Tuner card that has a ClearQAM tuner without the use of a DTA box from Comcast.
Comcast scrambles many of their higher subscription level channels. As the reviewer points out if you have a higher-end subscription (more than just basic), you need a cable card ready TV Tuner. Since you stated in your original post you have just basic channels, the any ClearQAM tuner will work for you without the DTA box.
Ahh... I think I see what you're referring to. It's the white connector at the top of the PCB towards the rear of the card. I'm not sure what that connector is for (front IR receiver maybe?). Brief glance at the documentation for the HVR-1600 didn't mention it at all.
Well as I said in my original response, the DTA box just converts the digital signal to an analog signal. Since the HVT-1600 has both ATSC (digital) and NTSC (analog) tuners, the DTA box shouldn't be required.