Amplifiers weight

Thanks everyone for inputs
I learn a lot 
so is not always about the weight 
some of emotiva and outlaw stereo amps weigh a lot my current amp A21+ weighs 72 pounds sounds amazing but anthem STR amp is too gorgeous  can’t stop looking at them
I don’t really need more power than A21+ for my current set up just to cover future upgrade
The Michi S5 looks great but 130 pounds no then I need to change my rack and I’m not ready for that  
The preamp looks amazing though for 4K

Aesthetix Atlas 70 lbs

The answer you are looking for is EXACTLY here by Nelson Pass:

https://www.passlabs.com/press/power-supplies-commentary-consumers

As noted, the size of the transformer is important. Inductors too, and heat sinks are heavy. The bigger the heat sink, the lower the operating temperature, for given heat dissipation.

The amount of real estate inside the enclosure is also important. If the big electrolytic caps are close to either the output transistors or the rectifier, or their heat sinks, they age prematurely. Obviously big enclosures weigh more.

If you live in a rich radio environment, thick metal is a good shield for your delicate electronics, although good layout can substitute. So again, all things being equal, heavier is better - the only problem is that all things aren’t often equal.

Finally, if a guest stubs his toe on 100Kg slabs of aluminum, that toe stays stubbed. Better that than the amp.