I took the bike back to LBS. I did not get to talk to the mechanic about it at pick-up. When I got back on the road, the problem remained, with absolutely no change. I'd like to give them some helpful suggestions when I return the bike. But again, I can't exactly locate the noise to a specific spot. And my own mechanical abilities do not extend much beyond the ability to change a flat.
Anyone have a similar problem, or could venture a guess at what might be happening? The noise is loud and incredibly annoying.