Your best bet it to buy the amplifier with the understanding that you can either:
A) Get store credit if you return it
B) Agree to an audition fee that will be applied to purchase if you buy it
This way both you and the dealer have skin in the game and he is guaranteed either a sale of something or a fee for his trouble. You get to audition the amp and not risk paying the 10K for something that just doesn't work for you. Win/Win.