I have that exact Radio Shack adapter here, powering one of my Netwinders -- which draw a LOT more power than my Empegs. Much, much more than beefy enough for the application.

Heck.. the stock mini adapters that were originally supplied are only 1A rated, so your 1.5A power supply is definitely overkill (just fine, use it!).

EDIT: The plug you linked to is the exact correct one as well.

Cheers