I tried engaging the tone shift and found I really like it. Especially at lower volumes and with both my Les Paul and Strats. Maybe it has something to do with the pair of Alinco Cream 90s I am running it through but it seems to really tame the highs and bring out some warmth weather using the clean channel or OD channels. Just my opinion and wanted to see if others use it? Also exactly what does the tone shift do as far as adding or cutting frequencies?