I've heard that this problem exists in the newer units; i.e those that have Pro Logic II. Again, my Kenwood 510 has the dropouts and (I'm told) the 509 does not.
I have the 510 and it's just OK. The Kenwood works fine but the input selection and remote is not as straight-forward as I would like and I'm still unsure about how it rates "spec-wise" since the power output is rated at a higher THD level than anybody else lists theirs. Kind of makes me wonder...