Critical VTA . . . !!!
Having made an upgrade on my P5 TT with the use of an acrylic platter mat, presenting a thickness issue? Standard felt mat is nominally 2mm thick, the acrylic mat is 3mm. You will have read how pleased I am with the improvements; 'old cynic that I am'.
The extra 1mm thickness bugged me . . . as such things do? . . . So I decided to try raising the arm by 0.5mm. Replacing the 1mm shim with one of 1.5mm.
. . . what a disappointment, the sound became boxy, lifeless and generally ordinary . . .
As the title of the thread suggests . . . VTA is critical, the difference is like night and day!