I had the same problem it tends to drive u crazy. Whatever outlet your using in the house isolate it from everything else. Then get a copper ground rod and hammer it into the ground just outside the outlet you’ve isolated . And that’s it hiss be gone, good luck
What cause tweeters hiss ?
I could hear hiss sound when i place my ears close to both tweeters (ATC SCM 11 speaker) when Denafrips Ares II is connected with interconnect (XLR or RCA) during power on/off/standby. Hiss sound disappear only until power cord is disconnected.
At first I thought it’s amplifier (Accuphase E280), then I bypass Ares II and connecting Sony CD player with RCA out to amplifier, no hiss can be heard from tweeters.
Due to curiosity, i connected my Topping D90 with similar arrangement, I could hear hiss sound until I unplugged power cord.
During the above test, music is stopped, amplifier is turned on but at zero volume. All my music source, DAC, amplifier are from the same power source/circuit with Novaris Power Filter.
Can’t hear the hiss at my usual listening spot though.
What could be the culprit that create this hiss, DAC ? Grounding Issue?