pasingit dodie...
@resident_evil, if the arm is parallel without the mat, what you need is a 2mm shim. i think rega sells the plastic vta adjuster which you can also use.
as with playing without the mat, the only consequence is that the lp might get scratch because glass is tougher than vinyl. otherwise you'll notice crispier sound than with the mat. if you like that sound, suggest you put a paper mat instead so as to preserve your lp then your vta problem is resolved.