professor

I use my IPhone to play my Sirius Internet Radio when connected to my X920 via bluetooth all the time. But then again my phone is a 3G

Try floating the ground. Sometimes there is a difference resistance between the car's antenna and the ground wire. some antennas offer enough gound to power a car stereo. Disconnect the ground wire from the chassis and see if the system still works. If it does, you don't need to connect the ground wire to the chassis because the antenna is acting as the ground.

I would try floating the ground....In other words; disconnect the ground wire from the head unit and the cars ground coming from the vehicle wire harness. Most head units get their ground from the antenna and when you ground it to the harness it causes the hiss you hear. Connect all the grounds to the ground wire on the head unit and non to the factory harness ground...No noise. You will know immediately if it works because if you dont' have a good ground from the antenna the unit won't power up Hope that helps.

I would try floating the ground....In other words; disconnect the ground wire from the head unit and the cars ground coming from the vehicle wire harness. Most head units get their ground from the antenna and when you ground it to the harness it causes the hiss/whine you hear. I connected all my grounds to the ground wire on the head unit and non to the factory ground...No noise. Also, the amp ground should be as short as possible and not have any paint on the body where the ground is connected...I usually scrape it off with a screwdriver under where the amp ground is connected...