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

Just don’t.

The risk of physical injury to either yourself or the amplifier by far outweighs any imaginary sonic benefits you might be hoping for.

As Clint Eastwood might say, ’A man’s gotta know his limitations.’

If you insist on being hardheaded, and as a fellow audiophile I would understand if in your search for audio nirvana you did, you could always follow in the alleged footsteps of Prince and his piano and employ the services of a giant crane.

There’s an example of someone doing just that here.

https://www.google.com/amp/s/www.dailymail.co.uk/news/article-3504617/amp/That-s-expensive-way-deliv...

Sound advice cd318

I like that hand cart on Northern Tool, but the video shows it going up the stairs without a load. Why wouldn't they show the guy with the boxes try to use it going up the stairs with the boxes? (even if the boxes are empty).
Hmmm...
B

"Why wouldn't they show the guy with the boxes try to use it going up the stairs with the boxes? (even if the boxes are empty)."

If the boxes are empty, they may fall, if they are full he may not be able to pull the cart up?

Carry one amp with your left hand and the other with your right.  It's super important that you maintain your balance and not get your spine out of alignment.  Also bound up the stair steps two at a time to cut the total number of steps in half.