I recently made the leap and purchased a PVR501 and am generally quite happy with it. I'm not a "power user" so a lot of the complaints I've seen on these forums aren't issues that bother me. However, there is one issue that is something of a concern. That is the noise this baby cranks out. I expected some noise as I have talked to others that have the 501 and they have indicated that the unit does make a slight hum. However, I did not expect it to be as loud as it is. How do I know if it is normal or if there is something wrong with my unit?