If you own certain models of liquid-fueled stoves, you may have noticed that they are quite LOUD in operation.  There is a reason why some users refer to such stoves as "Roarer" type stoves.

There may be a solution to this issue.  Quiet Stove

I have used these devices on stoves for which they are intended to be used.  While not rendering the stove absolutely silent, they certainly DO "Quiet" the stove a lot.   There is some anecdotal evidence that such devices aid in economy of fuel usage, and perhaps the ability to "simmer" using such stoves.

Pros:  Work as intended, and the items are both optional and indestructible.  Use 'em or not--your call.

Cons: Expense and weight.  Being indestructible incurs a certain weight penalty.  Again, user's call.

Not for nothing, but even some gas (Isobutane/Propane) stoves are much louder than others.  YMMV, but all other things being roughly equal, I much prefer "Quiet" stoves.  This is something seldom discussed in reviews of stoves.   I have suggested sound measurements of all stoves to some decent YouTube stove reviewers.  YMMV.

I have bought and paid for such devices for all applicable stoves which I own.

Disclaimer: No financial interest.

Examples of ones you've tried that work and the ones that aren't worth the money?

Bought one for my Primus Omnifuel, and worked as advertised. https://store.quietstove.com/select-stove/quietstove-burners-for-primus-stoves/quietstove-for-primus-omnifuel.html

This thread being made because QuietStove is offering most all their devices at significant discount.

Whether the devices are "worth the money" is up to the user.  Damn well "Worth the money" for me but cannot speak for others.

Bought another for my M1950 GI stove recently--not yet received.

I didn't realize it was one company, I thought you had tried several different brands.  Is it essentially just a diffuser that sits over the burner?  Makes perfectly good sense to me as some of the stoves out there do sound like a jet taking off.  I gave away my old Svea and I'm not sure where my MSR Dragonfly is at the moment; the Jetboil lives in the truck and sometimes goes in the pack but they don't make one for them.

Yes, a simple diffuser cap which sets atop the stove.

There is another mfr of these devices, but I have not bought any "silencers" from him:  BernieDawg

"Silencer"/Stove application chart:  Chart

His lineup is perhaps more extensive than that of the QuietStove people, so take a look.