maltesechicken

I have an Alpine CDE 9845.
I noticed that at the beginning of every CD / MP3 track that in the first second of the song there is noise. A very soft noise "clump clump clump." It is always 3 "clumps" in about 1 - 1.25 seconds of the beginning of the song.
If the song starts loud I don't hear it at all, but songs that start quietly all have it. It doesn't matter if it is a store bought cd, burned CD or burned MP3, it always does this.
I hear both in my front speakers and my sub so both pairs of pre-outs are effected.
Sound is there with engine running and off (although it is quite hard to hear when the engine is running - if that gives you an idea of how quiet and subtle the sound is). It is not major, but it still is annoying.
The Power IC of the deck is off, so that is not causing interference.
Any ideas? Is there something malfunctioning with the deck? Or is this common with the CDE 9845?

Thanks