2 specific questions about shipping 42 lb speakers within US

If you use factory packaging, that's a pretty good protection from damage.  The only further step you could take is ship them on a pallet, which is truck only.

I get all kinds of stuff shipped here from owners who do all kinds of crazy stuff.  The worst is peanuts, regular white ones, the powderize and shift and cover everything in dust.  Peanuts don't work in a big bag either, as they settle and the heavy thing in box drifts to the bottom.   

The best plan is cut up styrofoam blocks, bagged speakers so no dust, use the foam blocks to support ALL the sides of the speakers. and completely enclose it in a styro box, then a box that fits it exactly, no extra space anywhere.  This stops the speaker from moving within the box.  Then using cheap cardboard from Lowes or Home Depot is the worst- that won't work.  Got to uhaul, buy decent cardboard.

People want to save money on shipping and get their speakers destroyed over saving $50.   Having FEDX or Box Bros pack it doesn't work either.   Trying to hold the cones still doesn't work: it's not the cones moving that's the problem, it's dropping the entire box and have the voice coils move off center from the shock of the fall.  That's why palletizing larger speakers works, because there is a high chance someone will drop them, or if a tower type speaker, it will fall over, if not palletized.   With pallets, there is still the risk of forklift damage, but if its tall and heavy its a sure thing it will fall and get damaged. 

We are seeing high quantity of damage right now, as freight companies hire all kinds of inexperienced people. 

Brad

I would not use anything against the driver cones just use plastic wrap. One-inch Styrofoam should be sufficient but 2" better, 42lbs. is not that heavy. I've not used the shipping company you've specified but FedEx has been better than UPS for me.

Can't figure out Shippo.  Its offering looks limited.  Cost for UPS and USPS came out way higher on the CoolParcel website.  DHL could be cheaper but I can't figure out how to get a quote from Shippo.

Freight sites seem to not be better than CoolParcel.  One site deems my package to be a "parcel" and not "freight"  because it weighs less than 150 pounds; and they don't do parcels anymore.  Another site will give me a quote, but it was $1,100.  Versus CoolParcel's quote of $150. 

I'll probably just go with CoolParcel for the speakers.  And I'm going to check in 2 boxes on my flight as checked luggage (I'm flying to visit the friend to whom I'm shipping my speakers). They'll contain a receiver and a center speaker.  That's probably the cheapest way to transport the entire system.

A friend used Shippo to ship his Zu Dirty Weekend and had no issue. The factory packing is excellent however.

I would leave space between speaker cone and box.

I’m no expert in shipping but will tell you what I know. Shipping brokers can be really helpful, but I think they are mainly looking for volume. Thus, someone who regularly ships, like a manufacturer, is going to get a much better rate than you are as a civilian.

When I was shipping stuff back and forth to Slovenia, pre-Covid, Franc Kuzma could send something overnight, using his account, for less than it cost me to ship a cable across the country that was insured for low fair value (not necessarily retail replacement).

Shipping has gotten way more expensive in the last couple years. The bigger the vendor, the better their leverage if they pass it onto you.

For big stuff, I palletize, use wooden crates and air freight.

I knew a guy who shipped priceless cars all over the world by air- back in the day, it was 5 grand to load and fly one from NY to the Mid-East. Now, it’s probably at least triple that price.

If you are working with or shipping to someone who has a business account, they may be able get a better price than you.

Could you recommend a company? 

I would use a freight company instead of FedEx et al.