I have the Katana 50 MK II and it does allow you to switch from 50W to 25W to 0.5W as you were saying. As I think I said somewhere else, the amp is waaaay better than me. One thing I found out right away is that out of the box I got a lot of annoying buzzing and humming even on clean at low volume. Fortunately you can suppress it using the Boss Tone Studio software so it's pretty easy to solve, but still I was surprised to have to do that.