Ok, Clare, I decided to come back and give you a serious answer.
Yes, you may compliment your examiner on his piano prowess. However, there is a way to do it and several ways not to do it.
I am now going to tell you about the structure of a compliment.
Consider this:
You invite someone for a nice meal at your home, a meal you spend a lot of time and expertise preparing. At the end of the meal the guest says:
- Oh, That was delicious! What a nice meal you prepared!
This is probably what everyone unthinkingly does. Would you feel satisfied with that sort of compliment? Or would you feel a bit of an anticlimax, as if the person was “just saying it”?
Now consider this different response from another guest:
- I noticed that you used pine seeds in the spinach dish. They were roasted, were they not? I could tell by the enhanced flavour. And their crunchiness complemented very well the mushiness of the spinach. And I was wondering how you got the roast beef to be pink in the middle like that. How do you know when to get it of the heat?
I am sure you will agree that this response is much more satisfying then the one from the first guest. Interestingly enough, the second guest at no moment tells you if he liked the food, or if he thought the meal was good.
The difference is that the second guest is showing appreciation: his comments show that he paid attention and recognised the work you went through.
So , the structure of effective compliments is not to use vague adjectives that say nothing, but simply to describe back to the person you want to compliment in as precise way as you can manage, what they did. You see, complimenting people in this very effective way demands a lot of effort on your part. You cannot just gobble on the food and say “this is nice”. You must actually appreciate the food and inquire of yourself, what is it that makes this food special?
And if you avoid using any positive adjectives at all (as the second guest did), you will not only get the response you wish (the cook will be very pleased, I assure you), as no one can accuse you of sycophantic behaviour (as you actually never complimented the cook: you simply described back to him what he was already doing).
I would strongly suggest that you spend a week practising this form of compliment (if you are not used to it) with your friends/family – an d observing the amazing results – before actually trying it in your exam, so it becomes second nature and it does not sound artificial.
In fact I would suggest that you never again use the first form of compliment (it is not effective anyway) and from now on just use the second.
(This is what comes from feeling guilty about pulling your leg in my first post)

Best wishes,
Bernhard.