No, there is not a built-in code. But many of the one-for-all remotes can be upgraded with a
JP1 interface and some fiddling with the learn mode. Not difficult to do. I haven't bothered to do that myself since I have more than one working remote.
You know that the Kenwood KCA-R6A remote works, too, right?
Edit: On re-reading the above, it makes it look like I'm saying I haven't bothered to use the JP1 interface. Actually, I have used it, my JP1 remote is customized and reprogrammed to the gills for my home theater equipment. I just haven't bothered put a mode for the empeg on it.