Having worked for FedEx for 20 years and knowing the practices and operations of most all the carriers, the advice here is good.
If your speakers are under 50 lbs, I'd ship them FedEx or UPS ground packaged as mentioned with the corners double insulated with something like ULINE and of course insure them for as much value as you can prove should an incident occur.
If they are tower speakers and weight more, I would absolutely recommend a pallet and the speakers banded together with shrink wrap. You will have to ask for home delivery/lift service unless you hae room for an 18 wheeler pulling up to your house and for you to take them off the truck. Does this cost more? Yes. Bu haing been through a few tower speaker claims myself with bothe UPS and FedEx, it is not a fun procedure. They will do evverything possible to lower the price they pay you. So, in the end, the pallet method saves you a lot of heartache, 6-8 weeks of battling with thier claims people (UPS outsources theirs) and ensures the speaker make it there in safely.
I'm fond of FedEx freight/national and they do a good job and you can even negotiate discounts with them if they think you will be sending more speakers. Most businesses get 50%-70% discounts from them on the tranportation portions of the total shipping cost.
PS-Peanuts are the worst packing filler. Bubble wrap, styrafoam, air bags etc are much better.