Build a wooden crate or use a cardboard box for Amplifier.

We are moving and I have two amplifiers that do not have boxes. My concern of course would be damaging the amps during the move. I am probably going to be storing them for a couple of months. The amplifiers are Krell KSA 200s and a KSA 300s. Does anyone have experience in building a crate that they good lend some guidance ?
I have a full wood shop and are pretty capable.
Or would I be better off with cardboard boxes reinforced.
Any Help is gladly appreciated. 
Thank You.
if these 2 amps weigh alot, i would build a wooden crate. for insulation i would use that dense foam that is usaully in couch coushions.
For shipping my typical rule is crate over about 100lbs. Other than that double cardboard is fine if you don't use a gorilla carrier. Some hi-fi manufactures have gone to triple cardboard. Those Krell's are heavy, but if your using a moving company, my opinion is you don't need to crate.
You can also use expanding packs. Get a heavy double or triple thick cardboard box with at least 2-3 inches all the way around. Make it if need be. Just cut down from a HEAVY Refer box or something like that.

Use reinforced fiberglass tape to hold it together.

Put heavy styrofoam blocks in place to center the amps in the box. Tape them in place.

Get  heavy plastic bags and bag the amp. Set your expanding packs in place. Place the amp on the taped styrofoam and set off the bottom foam bags.

Set the top bags, set them off, close the box, but don't tape it.

Inspect your work after they set up and see if they need trimming or an XTRA bag or two

If you really want to go nuts build a 1.5 - 2 x 4" external frame with screws and glue. Remember don't glue what you're gonna take apart to get the cardboard box out of the wooden crate (has open slats).

I did the exact same thing BUT the inner box was lined with heavy felt and it was made of 1/4" ply wood and held together with leather belt straps..

I used that set up for 10 year traveling. Everything fit and was strapped to a dolly. A pair of MC30s and a C20, and all my needed STUFF. I NEVER broke a glass in all that time.. I worked on sea going tugs and mobile drilling platforms. It got rough out there sometime, pulling some nitwit off the rocks or foul weather hit...

Remember the Santa Barbra and  Exxon Valdez, I was there for both cleanups, what a MESS..

I double-cardboard boxed my PrimaLuna integrated using using plenty of foam and bubble wrap. It successfully made it across the seas by freighter with all tubes plugged in and intact.
In my industry we receive heavy weight pumps in a reinforced double thick cardboard boxes. The pumps are typically bolted to a plywood bottom. This keeps them from moving around and getting damaged in freight. 

You could cut a plywood base to sit in the bottom of a heavy duty cardboard box. Set the amp in the middle and put a 2" piece of foam panel on top. Take some perforated strap and run it across the top and use shallow wood screws to pin it down to the plywood base plate. If you get it sufficiently tight and use a box with a few inches of play around the outside of your amp it should be sufficiently sturdy for transport. In my mind at least 
You need to consider how you expect the carrier to handle it. I recently shipped an amp, but it was only 28 lb. I built a crate and used a single metal gate handle for it to be carried suitcase style. After going from AZ to MI and back, I was amazed at it's condition on return. (FedEx) It looked like it only went around the block.

If it is going to suffer impacts, wood will transfer more of the impacts v. cardboard, so you need to cushion the inner carton well. But a Krell is probably heavy enough that it won't be getting tossed around. I would assume hand trucks are going to be used and build to make that easy as possible. If it has to ship flat, I'd assume vertical forces are of the biggest concern, so you would want sidewalls capable of supporting a top panel that prevents any kind of crushing. Maybe wood sidewalls and OSB top & bottom.

If it can ship vertical with the heavy end at the bottom, I would do a riser on the bottom ends that allows a hand truck to easily grab it like a pallet. I found it to be quite the engineering task, with many considerations to factor in. Obviously you want to keep size and weight in check, ensure maximum protection, build it so it can be easily unpacked and repacked and the easier you make it on the shipper, the better it will be for your equipment. Insure for the maximum and slather it with"this end up" and handle with care stickers.

Contact Krell and ak if they will sell you a packing box for your units. A lot of manufacturers will do this. I know McIntosh does. You would pay for the boxes but they are designed for your particular units. FWIW
Box them individually with dense foam and strap it to a pallet. Make sure you don’t stack anything on top. 
I have a Krell KSA 300S which I have built a crate for. This amp weighs 185 lbs which makes it particularly hard to handle. I have all the original packaging but I built a crate anyway. Here is my experience:

I built the crate so that I could take the amp to the repair shop (180 miles away) because I needed to get it recapped. I did this because my experience moving the amp upstairs into my house was so difficult that I didn't want to go through that again. It's also stupidly hard to get the box into the back of a pickup or SUV and get it out again. People who have never tried to pick one of these up can't imagine how heavy it is.

The problem with any type of cardboard box is that there is nothing to hang onto. It is really difficult, even wearing gloves, for two people to carry a 185 lb. cardboard box that size. All I could think about was, "Oh God, what if we drop this."

The key feature of my crate is that I mounted two handles on each side. These are regular handles that I got at Home Depot and I used hardware that is suitable for the job. The handles make all the difference in the world. Two people can now carry the crate much more comfortably.

I pack the amp in the inner Krell box with the foam pieces and then put the box in the crate (I don't use the outer box but I kept it).. You probably can get away without the original box if you build the crate to the right specifications and use proper padding. However, when you are designing the thing, think about how you will get the amp in and out of the box. Using the original inner box,  if I ever need to ship the amp I can screw a lid on the crate, lash it to a pallet, and it should be hard even for FedEx to break it.

I used 5/8 plywood with interior angle brackets. I screwed and glued along all the edges and I put two coats of Varathane over the whole thing. It looks like it means business and is worthy of a $9000 amplifier.

I believe you can order packaging materials from Krell but I've heard that they are expensive. I would strongly suggest buying the packaging if they will sell it to you. Maybe I'm guilty of overkill but I've had my amp since new, it has been moved 4 times, and it is still in pristine condition. I'm really OCD about my gear and I would never forgive myself if I damaged this amp.

You will figure out the puzzle on how to pack the amp into the original carton and then put that into the box. You can't lift the cardboard box out of the crate so you have to gently flip it over, take off the crate and then unpack the amp.

Good luck. You are welcome to PM me if you want any detailed information.
A lot of moving companies do not cover damage to electronics. I would crate. Also, use insulation foam panels instead of upholstery foam. Try to build a cardboard box. Use the pink foam to surround maybe even double to 2” if you are really worried and build the wood box around it. You could use a 1/4 hardboard just in case you have a puncture on the out side of the cardboard box then foam then crate. Also, make sure the transformers are screwed down tight. When the move they get damaged. You will be happy knowing they are ok. Plus, if you decide to sell they are ready to go.
The key with any shipping container is to ensure that the contents do not move around.This is a large part of the battle.However if these are going to be shipped, wood crates would be the logic and ground freight versus one of the one of the carriers that use the 4 foot drop test to see if the product is packaged properly.

Also if you can remove the feet on an amp, get the bolt size, insert a bolt through the bottom of the crating with appropriate washers. Tighten that down. that ensures it won’t move in the packing.

Then the “cover” just protects the top of the amp from puncture/crush possibilities. 
I would crate the cardboard. You need a crumple zone to absorb the impacts. If you build a solid crate and the amps are fixed in a solid position they will still take all the hits and vibration. Just like a car bumper and a bike helmet they absorb the impacts through a crumple or break away material. Good luck and enjoy the music!
Since I ship heavy equipment weekly, wood crate and mount it to a pallet.  Can't be turned upside down or dropped like a box can.

Happy Listening.
Anything over 125 pounds you will want to go to wooden crate. Yet, Resolution Audio has been using wooden crates for their new Cantata and M100 amps for years. CJ switched to wooden crates for the ART27A amp. We at Penaudio just shifted to wooden crates for the new monitors. Look for local box company. They can make crates and supply foam. You will want 3" of foam to keep the amps safe. If they are going in a moving van, then tell them where and how you want them stacked.
lots of options here with most of them you doing the work. talk to the movers and give them your expectations / specs and see what they can do.....palletized , double wall construction with added padding for insurance should be no problem.....issue is the cost  
and the insurance....if you pack vs they pack what is the impact on any insurance issues ....if any