I bought a Whistler 3400 off of eBay, and am currently in the process of installing it. Right now it's just sort of hanging there, but that will be fixed tomorrow. Yes, I know it's not even close to the best you can get, but I got it cheap, and it's better than running with no detector. I'll eventually get something better, but for right now, this will work.
Anyway, my question is about the voice module. It seems like all the connections in the back of the unit are just 3.5mm (or 1/8") stereo connectors. Rather than buying the voice module, can I hook it up to my car stereo? I recently added an aux input, so I could just splice another line to the same input and hook it up that way. The manual says not to use anything other than the voice module, but I don't know if that's just a marketing ploy to sell their own product. I don't really care to invest more money in a radar detector that's pretty old, but if I can achieve what I want with stuff that's lying around the house, I don't mind putting the time into it.