My Sub is moving...

[vee]

Hey all

Ive been turning up the volume recently (watching aquaman and bohemium rhapshody blu rays) and Ive noticed afterwards that my sub has moved!
Moved like 5cm in an angle away from the wall...

Its a Sunfire HRS 12 sitting on tiles with the standard 'feet' that it came with

Any suggestions to stop this?

thanks

 

[KenMasters]

 

[vee]

 

[KenMasters]

 

[Juventino]

 

[BiZKiT]

 

[Katji]

 

[vee]

 

[Drifter]

 

[EJC]

 

[KenMasters]

 

[EJC]