I have a whistler xtr 310 and it didnt have a headphone jack built into it. I took apart the detector and put speaker wire on the positive and negative wire going to the built in speaker. Then, I drilled a hole in the side and ran the wire out. I stripped down a red and white audio cable for surround from a tv to a stereo and cut the other end off. I then put the positive wire from the detector to the red wire of the aux cable and then the negative to the white. To connect them i just twisted the wires together and used electrical tape. The "aux" cable plugged right into the aux input on my stereo and it works great. I can finally here my whistler over my four 12" subwoofers. The only problem is that it picks up engine noise when i accelerate or even use my windshield wipers. I'm going to be getting a new detctor this fall because the xtr 310 is little outdated, I was just a curious to see if i can fix this before i get a pro 78se this fall or maybe even a 9500ix.