Can speakers sound worse during break-in period?

Do I need to 'burn-in' my Harbeths?No: the only component part of a Harbeth loudspeaker that can change as a result of 'burning-in', is the resin-doped cloth suspension that centres the neck of the cone in the magnetic field - sometimes called the 'spider'. Under the microscope, once the resin-cloth has been worked backwards and forwards, it crazes into millions of small interconnected islands. This process is irreversible and takes only a few hours with bass heavy music played a little louder than normal. After that point, the drive unit can be considered fully stabilised with the resonant frequency settled to its final value. The ferrofluid used in Harbeth tweeters becomes appropriately viscous after a few minutes operation. Neither the coils, resistors, capacitors, cables nor any other part of a Harbeth speaker has any short-term ageing mechanism.