Auditioning Used Equipment - Am I crazy ?

Maybe you could have started your conversation with the dealer with something like this, "I bought a pair of XYZ speakers from you a while back and am now looking for and amp that would pair well with them. I see you have a used ABC amp listed on line in my price range and am wondering how that would work for me and if there's a possibility I could listen to the pairing?" Now you've presented yourself as an interested customer and not just a tire-kicker. If the dealer does not respond in kind, move on.

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.

I cannot believe the stupidity of this dealer. Follow me here, they're in Wisconsin and sell esoteric audiophile grade gear. Their available geographic market is halfway to Chicago to the south, halfway to Minneapolis to the west, and north to the border. How many qualifed customers do they have access to, a hundred, give or take? Now a qualifed  local walks in looking to buy a $10K piece of gear. Anybody with any sense recognizes this as an opportunity to build a relationship with a new customer. I hope the dealer reads this and realizes that this was an epic fail.

OP you are not crazy! Just look elsewhere you will find something even better and in 6 months the dealer will still have that amp sitting in its box

We don't know enough about the particular circumstances to say whether or not the dealer was behaving reasonably.  Most dealers have used gear as trade-ins on a purchase of new gear.  Taking in trade-ins is a BIG favor to customer and the dealing with the trade-in is a big PITA and often of marginal profitability.  One cannot expect the dealer to be quite as helpful with a used sale as they would be with a new sale.  If the trade-in model is current and of high value, it might be an easy sale, in which case, there is little incentive to unbox and set it up for any one of many prospective customers.  The amount of effort to make the sale is a business judgment based on the dealer's business practices and the particular circumstance.  The dealer would have to be concerned with tire kickers coming by to get a free "audition" of something not normally available in the area.

Ozzy62 makes a good point.  If both the buyer and seller have some skin in the game, there is less concern by the seller that he is just being used.  You should offer to pay a refundable fee to audition the amp.