Apparently this noise is normal according to Drake Canada.
"The popping sound when the radio is turned on is normal for the R8"
Thanks,

Shane Curry
Service Manager
Drake Canada
655 The Queensway
Peterborough, Ontario
K9J 7M1

Also according to a member of the Yahoo Group "Drake R8", message 1556.

I've owned an R8 since it was new in about 1994. The pop in the speaker
when turning on is normal and is especially noticable if the radio is in
the FM or AM mode. Ditto da bronx cheer. The radio seems to hold it's
alignment very well. If he's a Drake tech, you can believe him.

'Guess everything is as it should be, but if I had an audio amp that did
that everytime I turned it on, it'd be on the bench 'til I found the
problem. I find it annoying.

(The Bronx Cheer.... a medium volume, diminishing to zilch, fart sound)