Leave the slope at 47K and try raising the value of the treble cap from 470pF instead. Sky's the limit. Can even go as high as 4700pF if you wanted to. But try 510pF, 680pF, 820pF, 1000pF, 2200pF, 3300pF, 4700pF. Alternatively, you can lower slope resistor to 39K or 33K for more mids. But might...