How to physically move large heavy 100lb amplifiers easily (up and downstairs)

If going downstairs, why not take a page out of the courier company’s handbook, .....just push and watch it tumble down the stairs. 

@au_lait, Why oh why do some manufacturers make sharp heat sinks, especially when they are so large and heat producing that they often need to be stored on exposed stands?

Sorry for the slow response, but although I've been a reader of the Audiogon forums for several years, I've never felt qualified to advance a discussion until now. My bona fides: I was a contractor in a major metro area moving (High Value) special products for 31 years and recently retired. From multiple truckloads to items you could carry with one hand, as we say in the business "I've handled some things". 
First, no matter which method you use, your amp should be pad wrapped in a movers blanket, placed diagonally on the pad with the corners folded over on top and taped around in two directions with cheap brown plastic moving tape. Think wrapping a box with paper and tying with string. At this point you may just be able to pick it up with a helper and carry it. If not, then here are three mechanical options for this or any heavy pieces. (The fourth way is to call somebody like me, but that was already mentioned.)
1. Shoulder Dolly moving straps. They will take a bit of coordination between you and your helper, but they only cost around $40, and you don't have to worry about dirt and grit embedded dolly wheels scuffing up the stairs and scratching the floor. Practice with something else before you grab your (pad wrapped!!) $$$ amp. And make sure you throw the loose end of the center strap over your shoulder. Since this tool is meant for desks and refrigerators the strap is pretty long. Definitely doable.2. Yeats aluminum appliance dolly, or similar. A lightweight manual option. Rent-able in some places, but be sure to clean the wheels and stair runners before you drag it up your steps and across your floors. No telling where it was. If the amp is to short to catch the strap on the dolly, use a ratchet strap from Home Depot around the amp and hook the S hooks together in back. Your helper can wrap a strap around the axle of the dolly and help lift with that.3. Escalera StairCAT® Stair Climbing Hand Truck. I've used one for the last 20 years and, this isn't an ad, but if they asked me I would do it in a heartbeat. The model I have is the MLA-HC Stair Climbing Forklift, and it's battery powered for climbing stairs. I kept it when I sold out and still use it to get things upstairs. Escalera sells a metal plate to go over the fork blades, but as was mentioned in a previous post, you could use a piece of plywood. This is commercial quality equipment with a price to match. Good luck finding one available for rental, but lots of copier companies have them, and a smaller company might be willing to do your job for you. Again, make sure to clean the wheels and stair runners before use for inside stairs.
Good luck, be safe, and happy listening.

Wait....go back to Erik’s post.
can I get speaker cables long enough to reach the hifi dealer in Red Bank?
then I can ask him to connect my speakers to different amps every other day.

I have B&W 803 D speakers, purchased 15 years ago.  The dealer had two men deliver them to my upstairs listening room.  At the time I was in my mid 40s and in great physical shape.  I want to replace the speakers but since the I have had heart and back surgery and no way am I shlepping these downstairs for a dealer to demo in trade in.  I bought a 90 pound amp a few years ago and that will reside in my system as well until I move