As Elf73 suggests, it's very important to be able to document that the gear was made in a country covered by the NAFTA agreement (which would almost surely be either Canada or the U.S. if it's audio gear.) If it's not, or you don't have some proof of it, the delay can be substantial.
I brought a pair of ProAc speakers, made in England, from British Columbia into Washington state and spent at least 45 minutes trying to help the customs agents find the right line item in their catalogs listing what looked like tens or hundreds of thousands of foreign-made products. After all that, the assessment of $54 in import duty seemed almost completely arbitrary and I was glad to pay it to get out of there.
The agents were very nice and really were trying to do the right thing but the process made me realize if I were to do it again I'd make sure I was buying something that didn't require that procedure.