You can buy good, soft moving blankets from U-Haul. I use them to wrap my speakers and other vintage furniture. Moving tape sticks quite well to them so you can wrap them neatly and tape them up.
For moving our old Bozaks, which are large speakers like your Cornwalls, I put a sheet of double-walled cardboard that I cut to fit over the face (grilles) of each speaker to prevent any damage to them. Then wrap the blankets around the speakers with proper folds, etc. like wrapping a gift, and tape it well.
Be careful to not tape directly to the speaker with either packing or painters tape. I have seen where that stuff can take the finish off and leave lighter areas where the tape was contacting the wood.
When you move them, I'd suggest moving them yourself in your own vehicle like any other fragile/ valuable/ sensitive items you wouldn't want the movers to touch.