I posted a pic of it a few days ago. I haven't looked inside to know what's going on in there but I imagine it's simple. But yeah that little Marshal Studio 15 I have has a great round low end imo, and when I turn on the Tonefancier it actually is deeper than when it's off. I don't know how it happens and I've never seen this happen with any of my other pedals. I'll try to make you a movie in the near future.
To quote Studio Steve "There is no such thing as a bad pedal". You can interchange pedal with mic and amp too because he's said all three before. It's all application.

