Yeah, I've done this with the 40 and the Studio 40. The 40 was such a rattler that it was very clear the cab was the problem, but I tried it in another room anyway. Some of the high frequency buzz went away, but the jarring rattle was still there. Similar story with the Studio 40, so yeah, there's something in my practice environment that vibrates at a high frequency. But the lower frequency rattles have followed the amps around. The Studio 40 isn't nearly as bad as the 40, but it still can't handle digging in and sharp dynamics at certain frequencies, even at moderate volumes. It's usable for solo practice, but annoying when playing with others at higher volumes.
I've tightened every screw I can find in the Studio 40 (while being careful not to overtighten/strip), including the speaker baffle screws. I also took out the electronics, tightened things down on the circuit boards, and looked for wires or other objects that might vibrate against one another (and likewise where the wires connect to the speakers). All of this had no effect. I did a cursory examination of the glued joints (can't see a lot of them inside because of foam glued to the interior surfaces), but what I saw looked basically OK. Also rested the amp on mounts to get it off the floor and tried it on carpet and cement, all to no effect. Probably something that I couldn't easily see needs to be glued or fitted better internally.