A couple of years ago, I used R+L Carriers, having a pair of large JBL Studio Monitors (350 lbs) shipped from the midwest (Iowa), here to NM. They were very good, professional, reasonable cost. The large 53' semi truck had a liftgate on back, and also pallet jack, meaning you won't need the rental of a fork lift if the speakers are massive. Usually shipping to and/or from a commercial address will reduce shipping costs, versus to/from residential.
With large speakers, it is best that they are strapped to a full size Pallet with Nylon Straps. Mark
With large speakers, it is best that they are strapped to a full size Pallet with Nylon Straps. Mark