The needle
A worn or damaged stylus will ruin your records fast, and the first sign is surface noise.. but then it's too late! So if you are trying to convince yourself that the old Linn Karma you purchased back in 1982 still sounds great, then STOP!
Because a brand new hand-built Denon DL304 MC cartridge costing a mere £209 will have a much better (and fresher) sound, and save you from destroying all those lovely records!