If you use UPS, you will not be charged duty fees due to NAFTA, but you will have to pay UPS, who in turn will pay a broker to fill in quite simply paper work for the importation. It should not be excessive unless the value of the product in question is quite high. If the speakers are small and compact, you can do Canadian post...there must be a limitation in the size of package.
Someone else I know sent me a pair of huge Onken cabinets that weighted 120 lbs each on two large boxes that was packed by some commercial packer and the packer arranged to send it from Vancouver to NYC via DHL trucking....the packing and shipping cost about $150-I call that really cheap for what was delivered without ANY damage.