@rfprice - obviously there is some pretty strange grounding issues at play here and without being there it is difficult to advise on a solution
I noticed that the hum kicked in when I connected the interconnects from the DAC to the integrated. It didn’t happen when the components were merely plugged in and powered on.
This indicates to me that the DAC is causing the issue not the integrated
- did you try grounding the neutral side of the output from the DAC as I suggested above??? i.e.
- try connecting a piece of wire to the ground point on the power conditioner
- Also try the ground point on an outlet
- then touch the other end to THE NEUTRAL COLLAR ONLY of any unused RCA socket on your amp
- the hum should disappear.
(Although this still doesn’t explain why the hum didn’t happen with either of the other two integrateds that I tried.) --
This is because the other two integraed amps had a different grounding scheme
You say it only hums if you bypass the pre section of the integrated
- wih both DAC and itegrated plugged into the shunyata in any combination
- but IT DOES NOT HUM if the integrated is plugged into the wall outlet
- and IT DOES NOT HUM if the pre section is NOT bypassed
So I think you have one of two possible solutions/choices.
Personally, I have ONLY EVER plugged my intergated or amp directly into the wall outlet - it allows the amp to excercise if full dynamic prowess.
I no longer use a power conditioner of any type, just a power distribution box with no "isolatoin" or filtering, but I do have a device like the Shunyata Venom Line Defender to protect the gear from surges - I also have a surge supressor on my electrical panel
Sorry I could not be of more assistance
Regards - Steve