... sound batting and/or weighting speakers ...

I have  monitors and subs I massed load these and truly focuses the details.
i measured the dimensions went to a place that does granite countertops and picked out the granite I got Gee edges and just put a little blutac on top the granite adds a lot of mass and looks great I bought blue pearle from a Norway for $200 for the monitors, and $100 for each sub.

Just one quick point. 
 And not that this is really going to help the OP unfortunately. But it should reinforce the lesson learned.
 "There is just simply "NO", substitution for mass". You may address the effects as much as you will. But after fighting that battle enough times.
 I am sure you will come to this conclusion as well. 

Who needs a box? My speakers have no box. But gird all drivers with thick aircraft aluminium and you have something pretty spectacular. Sound and looks.
check www.kyronaudio.com.au and look up the Gaia. For subwoofers look up the Mercury. Frequency response 0.5Hz to 60Hz (-3db). Music? Spectacular. 😁 🇦🇺

Hello,
I like MilerC’s idea of the bluetac. Many times for computer speakers I have done this or added a cut mouse pad and put it under the speaker to clean up the sound.     You can take a sandwich bag and fill with sand, shot, or copper BB’s and open up the speaker and put the full bag on the Inside bottom of the speaker. You would have to do this through the plate on the back or the driver on the front.     Last you can put a piece of cut foam in the port to make a more sealed enclosure, but I am not a big fan because you are changing the frequency of the speaker and you will lose bass. You can try this by putting a sock in the bass port and see if you like this sound. If you do you can then go get foam and make it look better later. 

I have maggie LRS speakers. Very low mass and lightweight. No box. Ribbon drivers. They don’t vibrate at all so I’m thinking the vibration spoken of here is an inherent feature of dynamic drivers in wooden boxes. My previous speakers were Polk Rtia 5 floorstanders which were heavy ( 50 lbs ea) made of real cherry wood (not crummy MDF) had curved sides, and internal boxes and bracing isolating the drivers from each other and vibrated almost not at all.They had excellent sound quality, but they can’t compete with maggies. When I listen to them now all I hear is a box. Amazing how I never noticed this until I started listening to the maggies.
I had dynamic wooden box speakers for 40 years and never knew I was hearing a box until the box was gone!!! Not sure why maggies don’t vibrate. But the sound quality of them is like nothing I’ve ever heard before. Especially acoustic instruments. With loud distorted electric guitars, not so much. But that distortion is, IMO, an inherent feature of the instrument. The maggies make poor recordings sound awful. The Polks were much more forgiving. Everything sounded good on them.Also they really ROCKED, which the maggies don’t do. But I added a B&W 400 watt powered sub and that really helped out the maggies. They don’t have much response below about 60hz. But the mids and highs are probably the best you can get except for electrostatics which IMO have other drawbacks like they have to be plugged in and present a difficult load for most amps. My amp is a Schiit Vidar which works really good with the maggies. I agree with the others here who said instead of mickey mousing around trying to reduce the vibration you should either forget it and just enjoy the music or get better speakers.