Free trade
Remember the free trade agrement betwine USA, CDN and Mexico ? The big line was about to elliminate duty when we cross the border; not all of them but many of them. The way I understand is that the key point is, the product have to be manifacture inside these country. By personel experiance , I bought 2 pair of JBL e20 in the USA and them ship here in Canada ( for the price of one paire of e 10 in Canada)
because this speaker is 100 % made in USA it was free duty! but I bought a JBL subwoofer e250 and had to pay $20 for duty and I suspect that a the portion of the sub ( probably the ampli) is not from USA.
I am not a lawyer or a specialite in free trade border but it's base of what I heard and personnel experiance. I also found in our Canadian web page a manual of the rate about what and how the duty value is but belive me It's been writen by lawyer for lawyer
Good luck