Would you rent a $14,000 DAC for $75 per day?

I would  have no interest in this.

I’ll pass. 

Usually I borrow whatever for a week without any fee more than the cost of the travel or shipping. 

I'd rent. Great way to try out gear.

"But folks, you can rent virtually anything - cars, dump trailers, DJ equipment, $50k RED cinema cameras, boats, Ferraris, someone’s personal house, etc. Seems like the only thing you can’t rent is hifi gear. "

Not really the same. If I am a landscaper and need a Vermeer stump grinder or a forestry cutter, someone will rent me one and it is up to me to rationalize that cost to the project. Same with a RED camera. Both are rented as tools for a project. Renting a DAC for a trial is more like renting an article of clothing, except even then not the same. Clothing rentals are usually for a unique event and are done because the renter does not foresee an ongoing use case for the item rented.  I could see the service as an entree to purchase by a dealer (credit the rental charge to the purchase, if done.) A DAC is a permanent part of a system; you need one or you don't. If you aren't going to sell the same high-dollar DAC, why bother? I doubt there is that much curoisity to make a useful market. Of course, if you are looking to buy a stock of equipment  as part of a venture on paper, have a writeoff for the gear and occasionally rent the items, then that is a different issue. I can't see it making any real money, though.