The PDF document below has extensive information from Folk Alliance about the visa requirements for non-US artists attending FAI (and FAR-West) conferences.
Canadian artists attending FAR-West can come to music business conferences on a B2 visa, but must not have any paid performances during their visit.
FAR-West can provide an invitation letter to Canadian artists (upon request) indicating that they are attending a professional conference. This may be helpful when crossing the border.
Download Folk Alliance Visa Information