I may be interferece getting on your power lines . The transformer in that amp is apparently more susceptible to it than other amps. Check for any flourescent lights or dimmers being used that use the same circuit. It could be getting worse each time your refrigerator or heating unit kicks on too. Try to isolate the amp circuit from the digital and tv circuits.
I had a very high end integrated that had a similar "periodic" noise and the solution ultimately was teh manufacturer redesigned the transformer. In this case, it is not an option so the "preventive" measures are to attempt to minimize the noise to a tolerable level.
A power conditioner may help but my experience is it doesn't. I had some success with a PS Audio humbuster but not always. The humbuster is good at stopping DC noise but not much else and usually it is not "just DC noise" you are getting.
The gentleman who recommended "tack" I believe was referring to "Blu-tac" which is an expensive version of mortite (also available at places like HD or Lowes, much cheaper and just as effective). Basically you would use it to damp the transformer to tame the vibrations. With a toroidal transformer it is usually the internal windings that are vibrating so the noise will not stop but the damping may at least reduce the "volume".
HTH
I had a very high end integrated that had a similar "periodic" noise and the solution ultimately was teh manufacturer redesigned the transformer. In this case, it is not an option so the "preventive" measures are to attempt to minimize the noise to a tolerable level.
A power conditioner may help but my experience is it doesn't. I had some success with a PS Audio humbuster but not always. The humbuster is good at stopping DC noise but not much else and usually it is not "just DC noise" you are getting.
The gentleman who recommended "tack" I believe was referring to "Blu-tac" which is an expensive version of mortite (also available at places like HD or Lowes, much cheaper and just as effective). Basically you would use it to damp the transformer to tame the vibrations. With a toroidal transformer it is usually the internal windings that are vibrating so the noise will not stop but the damping may at least reduce the "volume".
HTH