I already owned a Sirius Sportster 4 portable w/ vehicle dock, so I didn't purchase the Sirius option. Here's my configuration: Plugged the radio power into the cigarette lighter power port and plugged the sound output to the aux jack of the center console. What I'm getting is a whirring/humming sound and it gets worse when you accelerate. Of course Mazda says it's the Sirius radio, but can't explain why it seems to work in other vehicles, of which I've tried. If I direct power the radio through my home power adapter, all is great, but I don't want to have to use a power inverter which will add additional wires to the mix, well that and it's bulky. Local Radio Shack guy (this is one where they actually have someone knowledgeble) said this is a common occurance in some Japanese models and that I need to get a noise filter which they didn't carry, but the one he recommended is at Crutchfield (http://www.crutchfield.com/App/Produ...35&tp=2653). Does anyone else have this issue, and maybe not with just a Sirius radio, but any other devices powered by the onboard power port? Also, does anyone know where I can report these problems, besides the FCC, where Mazda will actually acknowledge them and do something about it?

 

That's what I had to get..the exact same model...to quell the whirring noise from my Treo (I play podcasts and even use the phone while driving). Just get the Noise Filter and you'll be fine.