After cables, the preamp. I've had eleven preamps in and out in the last three years. More a case of buying used to demo in comparison to the one in place. The loser was then sold
What component have you changed out the most?
Which component in your two channel system have you repaced the most? Sice I started this hobby (16 years ago), I have gone through more digital sources than any other component. A close 2nd would be amplifiers.
KF
KF