Greetings, fellow players! It's almost a year since i bought my Katana 100w Head. I read everywhere that volume and master knob on Boss Katana might affect your tone, depending how you set them. Some say that you should maxed out the master for the best tone, some other say that you should peg the master. If i remember correctly, even Boss' own product person said that you should start with volume and master maxed out to get the best tube like sound and then use the power control to attenuate the overall amp volume. Last few weeks, i've been re-reading a lot of articles about how to set a good tone on Katana. It drives me crazy. I couldn't wait another day to find out wether the volume or the master will give me better clipping, compression, and harmonics. I never had any time nor proper motivation to do a test before, but today i spent my sunday doing several run to test those arguments and the conclusion i get (tl;dr is that both volume and master do not have any effect to the tone. This is what i did: I use a MIM Telecaster stock on neck pickup, put a looper in front of Katana running to a Marshall vertical cab with Celestion Seventy 80 speaker, set the amp on clean channel, set gain, volume, and master at 12 o'clock, play short notes and chords (1 or 2 seconds so i could hear the difference better), and loop 'em. I cut the volume to almost 0 hoping to hear some clipping and compression. The result is no, i didn't get any. I dial back the volume to 12 o'clock and this time i cut the master to minimum, still nothing. I leave the master and peg the volume, it sounds louder but still nothing changes (sounds exactly the same, the compression, the overall tone, the harmonics and overtones). I did this several time, using the power control so i could hear the difference better (at minimal volume or master, it's hard to tell the difference if i'm not using the power control). Next, i set the channel to crunch, set the gain accordingly until its clean when i play normally and slightly break up when i add a little more power to my attack. I strum a short clean chords and hit several notes, do the same as before, hoping that it will break up when i change the volume or the master knob... still nothing happens... it all still sounds the same (i didn't even move my ear to be able to tell if there's any difference in compression, harmonics and overtones). Last, i use the lead and brown channel. Those channel have more range of clipping and compression. i first thought that if a small changes in guitar volume knob will give you a lot of changes in terms of clipping and compression on those channel, a huge swing on amp volume knob and master should at least give me an observable changes. Did the same as before. No... nothing changes. After all those test, i conclude that the only knob to change the shape of the signal's wave form on Katana is the gain knob. Volume and master knob only changes the overall volume, and i believe that there's no such thing as pre-amp or power amp volume. If a should guess, the channel volume purpose is to set all of our patches volume on the same level, and the master is for us to be able to fit the overall volume of the amp fast. I don't know why the need to put the power control knob. I'm not a professional player, nor an audio engineer. Just an amateur that love playing guitar. So there's a lot of chance i might be wrong (on my method, knowledge, or my ear). I just want to share the result because me myself have been confused by a lot of articles on the internet, and i don't want anyone using Katana spending hours of their free time reading different articles on the internet and still not convinced wether they should maxed out their volume knob, their master knob, or declare a war with their neighboors by pegging both (even on 0.5 watt mode, the brown channel will make you an enemy of the state) like me. So i made an account on this forum, and here's my first post. Hope it could help anyone.