You are happy with what you have. His buisness is to get you to buy new equipment. You weren’t looking to buy a new amp. If you spend $300 for an audition, your emotions will effect your perceptions-you will want to hear an improvement to justify the expenditure.
Then not being able to actually audition the component itself is the icing on the cake. Monoblocks at twice the power of the stereo amp he wants to sell you. From what I’ve read of the Tritons they do better with more power. The difference between 30 and 60 watts is more meaningful than say, the difference between 150 and 180 watts.
It sounds like he smells blood in the water. Audiophiles are notoriously gullible, and in view of your 83 years of age he probably figures you are an easier target