I owned a pair of 33H's for 9 years. There was never an issue with buzzing and hiss. Are you sure there haven't been any component or wiring changes in your system, which might be causing ground loops or picking up RF?
However, I believe Ellyjr's observation is incorrect when it comes to the 33H's. The problem to which he was referring applies to the 330 series amplifiers (331-336), where the capacitors definitely go bad after a period of time and have to be replaced.
However, I believe Ellyjr's observation is incorrect when it comes to the 33H's. The problem to which he was referring applies to the 330 series amplifiers (331-336), where the capacitors definitely go bad after a period of time and have to be replaced.