Hey kevine, I have a thought that may be helpful...
When we fostered a new kitten last year, I was concerned about both potty accidents affecting my speakers, and the possibility of the cat doing scratching and clawing at the base of the speakers. So we placed decorative pillows around the bases of the speakers, the kind you buy at a Pier 1 or place like that. Not pillows that look like they belong on a bed. Sure enough, during play time one of our older cats got spooked and hit the base hard enough to knock it over, but the pillows were there and they cushioned the fall. It wasn't even what I intended them to do, just an unexpected benefit. Now, your Silverlines are larger than mine, but the same principle applies - if you can't keep them from toppling, make sure they topple onto something soft and forgiving. It may seem odd - and I guess it is - but if you find decorative pillows that match or enhancer your listening room's decor, and you just sort of spread them around the speakers, next time they come down they may just land on pillows. Best part is the pillows are temporary, they don't affect the integrity of the speaker cabinets, and they're at ground level so shouldn't change what you're hearing either. My ex-wife's sister used to decorate with pillows all over her rooms, and it always made her place seem warm and homey, so I was just copying her!
When we fostered a new kitten last year, I was concerned about both potty accidents affecting my speakers, and the possibility of the cat doing scratching and clawing at the base of the speakers. So we placed decorative pillows around the bases of the speakers, the kind you buy at a Pier 1 or place like that. Not pillows that look like they belong on a bed. Sure enough, during play time one of our older cats got spooked and hit the base hard enough to knock it over, but the pillows were there and they cushioned the fall. It wasn't even what I intended them to do, just an unexpected benefit. Now, your Silverlines are larger than mine, but the same principle applies - if you can't keep them from toppling, make sure they topple onto something soft and forgiving. It may seem odd - and I guess it is - but if you find decorative pillows that match or enhancer your listening room's decor, and you just sort of spread them around the speakers, next time they come down they may just land on pillows. Best part is the pillows are temporary, they don't affect the integrity of the speaker cabinets, and they're at ground level so shouldn't change what you're hearing either. My ex-wife's sister used to decorate with pillows all over her rooms, and it always made her place seem warm and homey, so I was just copying her!