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

None....I repeat None of these tweaks will work unless blessed by the Pope!!!!!!!

Seems like a lot of ground has been covered but Mr. Darko also made quick vid on them. https://youtu.be/Dvz2SaHzn3U

Speakermarster says it very simple as it is.
my hifibuddies and  myself are using many of these ressonance tweaks and one of my favorites is Ebony blocks about 12x12x6 cm.
by using diffrent materiale and sizes we alter the sound and i sometimes adjust acording to the volumen i play at and the type of recording i am lisining to.

Reading some of the comments make me wonder why some people cannot hear these for me obviously differences when you are damping or undamping the chassis of a component.

Could it be that some systems simple have too many constrictions in the signalflow so you need to find these before you get the bennefit from a more optimised chassis
. I think to observe that  one of the trends in ultra highend is that the chassises have become more and more in focus and clearly better optimised.

One of them could be seen with the step from the Audio Research 40th Anniversary to the Ref 10 preamps where the Ref 10 had so much more focus on the chassis. Both models acted very much when you removed the topplate or when you dampend them with  reconance tweaks.

Its a very cheap tweak but i takes a lot of time to find the right material and the right spot to place them. 
It obviously that diffrent chassis need diffrent tweaks.

By the way i feel the same way with the windows in the lisining room, tweaking the glass ringing makes a clear difference in the sound of the room and thereby the sound of the music.
So another nice challange and never ending story for the audiophile

@rushfan71

I use 1 pound bags of cannabis.

Yeah, but the bags keep getting lighter everyday

Don't knock it till' you try it: cryo'd antimatter carefully balanced on top of a Stillpoint- Soundstage will extend beyond your walls and wrap itself around the planet. 

@spencem best solution and best answer. lol

@rushfan71....kilos are better, but...

See you shortly....;)

@mitch2 
I'm very proud of how tightly they're packed.

@spencem - I hope your vial holds a lot of those little suckers....  
At 0.000000000000000000000000223 kg each you might need to mass load your mass load.

One of the cheap tweaks I would use was to open up a cheap CD player and coat the inside walls and top with plumber’s putty. It would add about a kilo of weight to the CDP and dampen (reduce) the vibrations.

On most players it would make an immediately subtle, but noticeable, difference.

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

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 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.

😌

@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.

;)

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

Black light posters, speakers in nets, lava lights...real tweaks. And those light machines that synced with the music. True enhancements. Not a bunch of boring rocks hyped by equally boring mass loading shills. No mass. 

I use empty, crushed cans of Guinness on my components.

I get dynamic, expansive, 3D memories.

Add "bee bees"!?  Talk about introducing a "buzz" into an audiophile system....

Mass loading is a load of tripe.  Pure snake oil.   As others have mentioned; I sometimes place heavy objects (the stainless doorstops work nicely) on small electronics to prevent the cables dragging them around.  

I also do this for my multiport USB chargers.

A bunch of us tried this tweak and it worked pretty good: purchase a big container of bee bees and multiple small plastic containers that measure 2”x 2”x 2” and fill this little containers with the bee bees. I placed multiple containers on each piece of equipment. A $20 tweak for multiple components.

mass loading can help some equipment, can affect SQ

but as mentioned below... lots of streaming gear (and some phono stages) are small and light, need something on top to hold them down so cables can be attached securely and don’t shift stuff around

The community will benefit from my most recent article for Dagogo.com just submitted a day or two ago. It will take on the subject of mass loading and several other tweaks. 

VPI brick blah blah honk honk.

 John Darko no.

I’ve tried Herbies Audio Lab Stabilizers (or two stacked). Pre, DAC or ss amp, but I always end up removing them after some time. Same outcome every time; a bit more clarity and delineation but slight negative affect on soundstaging (within, not overall size) and also a slight loss of the organic flow I have... It’s a fine tuning tweak that not all systems need or can benefit from. 

Brass is a popular audiophile material used for damping electronics (and as footers under electronics and speakers). Brass weights with a thin cork or elastomer backing are sometimes used to reduce resonances from undamped metal chassis tops covering electronics.  Some use them on top of speakers to drive cabinet resonances to a lower frequency or to damp flimsy/thin speaker cabinets.

He has stated they are just "paperweights" to keep the small stuff like streamers and DACs from moving with stiff cables. Not "mass loading" baloney.

I’ll hazard a guess that the “mass loading” has more to do with keeping these light little boxes from being pulled from their place by connected cords.

I prefer a more organic approach to mass loading (recent system pic)...

https://www.culture24.org.uk/asset_arena/8/71/06/360178/v0_master.jpg

DeKay 

John Darko the youtube reviewer has them on all his equipment.

I would not buy any of these items unless they have undergone cryogenic treatment and quantum cleaning. Be sure their astrological sign is aligned with yours.

And the most important one, sits on the top of his head.

Cheers George 

Added mass for vibration control, can have a good effect on tubed units and power supplies. Good thing is that you can try and use something without spending a cent.

G

I would not buy any of these items unless they have undergone cryogenic treatment and quantum cleaning. Be sure their astrological sign is aligned with yours.

I kid you not. They sell bags of rocks. 160. usd. My setup would have taken 1600.00 worth of "ROCKS" to load my speakers properly.

390. each x 5 bags x 2 = 10 bags of rocks for 1600.00 usd.. Nice bags though..  I like the idea, just not the 1600.00. OH They had "Earth Boxes" from 1k - 10k.. NO KIDDING.. Box of dirt.. 10K.
I'll take 5.. Keep the change!

Cabinet material makes a difference too.. My Elixirs are HDF. Go tap on the side walk.. about the same.. The monitor section, 390 lb..

Regards

This is a form of mass loading, a type of vibration control. Nothing special, just solid mass. Looks better than a phone book, one of the first I tried 30+ years ago. That's how old this is. You can try a book, dive weights https://systems.audiogon.com/systems/8367 lead shot, granite, butcher block, sand bed, literally anything with mass. Not all materials sound the same. 

Look close, you will notice I have done this with a lot of mine.