Theoretically, with couriers, there should be no duty on a Simaudio amp because it's made in Canada. However, the form has to be filled out exactly by the seller and the $7/hour clerk who has been working there for a week might still want to argue. If Simaudio is willing to send a letter to them, on your behalf and stating they are Canucks, you have a valid recourse.
Standard postal cargo does not have additional charges but there is risk of them leaving at the front door when nobody is at home.
There are weight limits for mail and most of the couriers. I forget what the exact numbers are but that can be googled. There are also size premiums that get ridiculous if over 4' but shouldn't be a problem for amps.
There is taxes, both PST and GST that the couriers collect. Not sure how that works with postal service.
Neither UPS or Fedex will insure for damages on used equipment, only loss. If the packaging shows damage, they might insure but the package has to confirmed at delivery and that's just the start of the hoops to be jumped through.
UPS and Fedex charge brokerage fees as additional on all ground freight but include that charge in air freight. For something as heavy as those amps, air would be very expensive.
Many people have a mailbox on the other side of the border and drive across because shipping is much less expensive within US.
Warning: Do not declare the item for reduced value to avoid taxes. They have both guns and computers at the border and will confiscate if they confirm fraud.
Congrats on the purchase.
BTW, There usually isn't a problem with Canadian money orders in US funds, except in Backwater, PA, but if you're ever selling to someone in the States, insist on an "international" money order.
