Hi Guys,
Back from Cedia.
The NRB and NPB were names made up by our shipper at the time. We were moving from the standard 2B, 4B' 3B's etc. to newer designs and we were concerned that the old and new versions of the amplifiers would get mixed up in the stock room.
So Peter our shipper at the time decided to write NRB and NPB on the side of the newer amp shipping boxes so he would not mix them up. The 'NRB' stood for 'NEW REGULAR BALANCED' and the NPB stood for 'NEW PRO BALANCED'.
TRIH - (The rest is history)
james