It really does what everybody says around in reviews and videos, I can actually practice at midnight without disturbing anyone. Just like TV volume.
A simple example I can give, I have a MacBook Pro, I can play a song on iTunes at a volume level, let's say "6 clicks of volume" Well more less that is how loud a trumpet would sound with the Wallace damper. I definitely advise it!
Thanks to its foam ring it attaches nicely and firmly inside the trumpet bell.
And it is actually adjustable, it has a removable part which allows you to control how high or low volume you want, 3 levels.
Im not an expert, but they say it affects the tone for about half a note... It is also a bit harder to blow the trumpet when using the mute, but just a tiny little bit.
Yeah, could be, I think so, but again, it is priceless that you have the option to practice at home without disturbing neither the next room neither the next flat.