I've just had a London Power power scaling box installed in my Ceriatone 18 watt trem Marshall clone. WOW! This thing really works. First a little background. My 18 watter is too loud for rehearsal. So far stage volume has been perfect, but I'm always scared of running into the uncooperative sound guy. In rehearsal I've been knocking a few db's off with a Weber Mini-Mass. I don't really like it. Even at minimum attenuation, it changes the tone. And at any significant level of attenuation, I loose high end and everything becomes super compressed. Someone compared playing through an attenuated amp to drinking through a straw, and that pretty well sums up my experience with the Mini-Mass. Some people say that different attenuators work with different amps, so perhaps the Mini-Mass just isn't a good match for my amp. No matter. I had my amp tech (who's quite an accomplished amp builder himself) install the power scaling box. He was pretty skeptical and give me that a-fool-and-his-money look. After he installed it, we were both amazed. Up until very extreme levels (sub loud TV levels) the amp sounds EXACTLY like my amp when its cranked only quiter. Did I say exactly? I meant exactly. Really, it's astonishing. There is really nothing more to say about it. No artifacts. No coloration. No tone suck. No compression. Just like my amp but quiter. Wow! I have yet to have a full band rehearsal with it. (Drummer is on vacation.) When I do and after I gig it, I'll do a follow up post. But damn, as of right now, I'm thinking that this is the holy grail of volume control. All of you bedroom players and studio-only types take note. This works! And all those amps that I love but only break up at too-high levels: Bassman, JTM-45, Hiwatt, Super Reverb --- all these are now realistic options. Install power scaling and you can actually use these beasts in a real world context (and still have all that power on tap if you need it). The only downside with this particular installation is that the box goes on the side of the inside of the cabinet (my amp is in a combo). You have to reach around back to change it. I am anticipating that this set up makes altering the level of power scaling a bit of a hassel on stage and in rehearsal. But I tend to just dime the thing and control my volume with the volume knob of my guitar. Still, it would be nice to have easier access. Executive summary: I love it!