What are all these metal cans/pods sitting on top of electronics?

They are a tweak for vibration and resonance control in components.

@dekay , one might muse that one art leads to another? 

"...the turntable is under that cinderblock config over here.  I haven't seen my amps for over a year now.  The steel I-beam spanning the speakers is starting to flex the floor, so I'm looking on putting some concrete piers under them in the crawl space...."

Nothing Exceeds Like Excess.  A variant of the Completion Backwards Principle.

;)

I use 1 pound bags of cannabis.

I found that a sativa gives the speakers a more lively, energetic presentation.

While an indica presents a more laid back, relaxed sound.

It's really up to personal preference.

😌

I mass load my tiny novo headphone amp with a decorative bronze statue of a mermaid sitting on an amber colored marble base, very nice looking and heavy. Only reason is the amp is light weight and tends to be pulled on by the interconnects. Now its steady and planted like a rock. Does it sound better? Hell if I know.

I use a small cylindrical vial of Higgs bosons on top of my equipment for mass loading.