Sometime ago I listened to a radio documentary where a marketing company figured out the optimum length of time to offer a product as a free trial. In this case, "optimum" meant 'long enough that the consumer felt they could buy risk free but also long enough that the likely hood of the consumer being willing to return the product, was greatly increased."
My opinion is that a stated "break in period" is designed to serve much the same purpose. Eventually, you get used to them and the thought of going through a return cycle starts to feel less inviting.
Trial periods, however, are great especially for the consumer in this new online purchase world. One just has to enter the transaction being mentally prepared to take advantage of it if you don't get exactly what you expected.
By the way, this radio documentary is a weekly show on CBC radio that talks about marketing. It is quiet aptly named "Under the Influence."
An interesting analogy and no doubt quite correct, however, when it comes to the topic at hand, speakers, most of these companies still sell through retailers and it is the retailer that determines any sort of return policy, not the manufacturer. Unfortunately, unless you have some sort of arrangement with the dealer, after you buy them and take them home and use them for awhile, the best case scenario is an exchange, not your money back.