Maurhifi
New Head-Fier
Your issue could unfortunately have a lot of hidden causes, let me try to summarize and apologize for so long list:
1. Hauris HS2-SF has a very good power supply, but it does not mean "totally" immune by network harmonic pollution... did you installed recently some new eletric device in your house? New refrigerator, microwave heater/oven? Or simply another hifi gear close to HS2? If yes, try to disconnect it and try to see if you listen the humm any way.
2. If answer to p.1) is no, pollution could arrive from your house outside network plug. Try to disconnect and try in another plug in another room... usually this test does not bring results... but try anyway
Do you live inside or outside a city?
Before to suggest you to purchase a network galvanic transfomer separator, that just and only would remove DC components in your network low voltage feed, let's analyze also:
3. Tubes could be the reasons, why not! They could generate a resonance loop, further amplified. Do you have a new set of tube to test?
4. If also this test does not drive to any results, prob could be in the power transformer in HS2 unit, but in this case, it needs to be opened and checked by a expert service shop... do you have someone close to where you live?
In theory, nothing could be excluded if not deeply investigated, neither a potential MHz element from a radio source... that has been my issue in the past, but it's IMO a remote chance with HS2, since good cable shield.
Let me know your opinion and if you succeded in something...
