An Olive NAP 250 is an enormously capable amplifier, but will need to go back to Salisbury for service/recap to give of its best, if this has not been done recently (with papers to prove it). Do remember to factor in the cost of this when buying the amp.
This is perhaps a good example of why one should always take other people’s suggestions with a pinch of salt. One person’s massive upgrade can often be someone else’s minor improvement. It can, of course, also be system, room and loudspeaker dependent.
There are also considerable differences between 250s of different generations. Older models, especially chrome bumper and olive, will vary from one amp to the next just because of their age. They also differ from the more recent Classic 250.2 and 250DR which both have a higher power output and an ability to drive more demanding speakers.