Can anyone else familiar with Clayton chime inThree types of noise I have heard from amplifiers include transformer hum, 60 Hz buzz/hum, and high frequency hiss.
Transformer hum will occur with toroidal transformers that are subjected to DC on the power lines. The larger the transformer, the louder the hum. Plitron makes a LoNoise transformer that is expensive but will largely eliminate this hum. The Claytons use two large transformers per amplifier and are indeed susceptible to that type of hum when DC is present. DC on the power line is not that uncommon an occurrence and can result from a variety of factors, that may or may not be associated with things going on inside of your residence, as others here have pointed out.
The 60Hz buzz/hum is, in my understanding, most often a grounding issue. The Claytons do not play well with anything but a balanced signal. Forget using rca/XLR adaptors or the Claytons will buzz like crazy. I got around that issue by using Jensen input transformers to convert the single-ended signal from a Tom Evans Vibe into a balanced signal.
Hiss from the tweeter is related to the amplifier's noise floor, amplifier gain and sensitivity of the speakers.
Clayton implemented a power supply upgrade that includes new toroidal transformers, and a rebuild of the power supply. Before having that upgrade performed, my M300s were quite noisy but, after the upgrade, not so much. However, they were never as dead nuts quiet as my current Ncore amps or my DNA-2 amplifier. Neither of those amplifiers can ever be heard through my speakers when they are at idle. The DNA-2 has a very large toroidal transformer which is quiet most of the time although, on occasion, a very slight mechanical hum can be heard right next to the amp, but not at all through the speakers. The Claytons never achieved this level of quiet, although they did sound good with music playing, as do the other two (quieter) amps mentioned.