This is the third SNI-1/3.5 I've bought, and they seem to work great for the first year or so and then the audio quality begins to get muffled and I have to buy another. I should note that I use this unit for my music input in a small (noisy) airplane, and there's lots of vibration the unit needs to deal with. So that said, it's seems to be a good unit but wouldn't recommend it in a high vibration environment.

I used to conect a dvd tru my factory aux, and take at lease 40% of the feedback.

My VW has an audio input which I use for my Siruis s50 sat. radio. Before using this device any acceleration / deceleration would register through my loudspeakers. With this device in between the radio and the sat device all hum was removed, however this device appears to be failing only after 6 months use.

I bought this filter because of engine interference when I play music from my car. This filter filters out the vocals of my songs. It may work in other cars but it did not work as expected on my Corolla.