Used home audio speakers are freight class 100 if I recall properly. The problem I encountered when looking at shipping my speakers freight was that the companies would only insure for 10 cents per pound since the speakers were used. So they'll insure your 175 lb cargo for $17.50.
FedEx has a freight service, but they were more expensive than FedEx Ground. I ended up shipping my speakers (150 lbs each packaged) via FedEx Ground from Mobile, AL to San Diego. They arrived undamaged, but I had the original boxes and packaging material. I also beefed up the packages with some plywood inserts as well.
You could always look into taking the speakers to a FedEx Office location and let them package the speakers. It might be pricey, but they're totally on the hook for any damages since they packaged them. Just a thought.
FedEx has a freight service, but they were more expensive than FedEx Ground. I ended up shipping my speakers (150 lbs each packaged) via FedEx Ground from Mobile, AL to San Diego. They arrived undamaged, but I had the original boxes and packaging material. I also beefed up the packages with some plywood inserts as well.
You could always look into taking the speakers to a FedEx Office location and let them package the speakers. It might be pricey, but they're totally on the hook for any damages since they packaged them. Just a thought.