"Many don’t realize this, but carriers (at least UPS) will only insure for damage if “they” box the item up themselves. Even if i box the speakers or any other item in its original container, all insurance covers is a loss by the carrier. "
This policy may vary by carrier and even locality.
This past fall, I shipped a $6K amplifier with Fed-Ex Ground in the original double boxes. It was accepted by Fed-Ex as fully insured. The receiving clerk did examine the packing before approving it, though.