This thing brings out the bass notes that you were not aware of, which is cool. Not bad for the price. Unfortunately, there is one downfall. Once your engine is on, there is the irritating engine noise that pops its head up. I tried removing the audio cables from the unit and the noise would go, but as soon as it is attached to the amp, here is the noise. I tried installing a noise filter on it, but it only turned it down a little. Now, each time I open the door, i get an extra ping through the speakers and when I turn off the vehicle, there is this temporary hum that filters through the system until tthe unit powers off. No ground selector on teh unit as mentioned in the manual either. But for the price, what the hec...