F5 buzzing issue

Dear guys,
FInally, i have made F5 - took the longest time ever....
Aynway - when i connect the amp input to ground - it does not buzz...
When i leave the input of the amp open - it does not buzz....
When i connect the source to my F5 amplifier (i am using M2Tech Young dac with variable output as a dac and preamp right now) - it does buzz... i an listen to music but it buzz....
..
My amp boards are from diyAudio store
Tried to connect the 10R resistor on the amp pcb and that to my signal ground... it did nothing or very little....
will attach the some pic's and grounding schematic (sort of)....
thank You all for your time.....

edit: on the inside - two smaller boards are soft start and protection from Welleman
 

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Might want to start with one signal board at a time.

Is the hum on both channels or just one?

Are your leads from the RCA inputs to the signal boards shielded?

Have you tried hooking up a different source to see if the hum is still there? A smartphone or a laptop will work just fine to test.

Yes, interconnects should be shielded.

What are the extra set of RCA jacks for?
 
On both channels, same loudness and only when preamplifier/dac is connected.
. when i disconnect it or ground the input, it does not buzz...
leads from rca inout jacks to the board are shielded on one side (on rca jacks side)...
...
Haven't tried a different source...
I only have interconnects that are not shielded..

If this is the problem, i should go and get shielded interconnects...
Has anyone tried interconnects without shielding on F5?

I have only one set of rca jacks... one for each channel...
 
Thank you for you kind reply Nelson.....
Chassis will remain hard on earth ground... i have cl60 connected from chassis to my amplifier ground and signal ground but for some reason it is buzzing... only when i disconnect the interconnect to the source, it stops.....
i suspect maybe because source - ground loop with source.... ... not sure.... will see