Roksan Attessa Streaming Amplifier Review

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I'm pretty sure we are seeing a GND topology error on that amplifier PCB. The field emitted from the AC feeds won't be the main culprit. While not twisted, the wires are still close enough to each other to produce only little magnetic field. Same goes for the field from the tranny itself (toroids can have issues with beams in certain directions).

IMHO even within the given constraints, a simple redesign of the amp+supply PCB layout could yield 20dB better results.

They did what you said. Few months ago when I tried to connect wiim pro plus to my attessa with a qed coaxial cable I experienced very little static and seriously bad intermittent audio. Tested the wiim with other dacs with the same coax cable and it worked fine. In my case the coax worked fine only when I was connecting in parallel the analogue output of wiim to the analogue in of the amp with an rca cable which was working like a ground connection. I have talked with Monitor audio support and they offered me (for free) a redesigned pcb that solved both the issues of interference and the very faint buzz on the right speaker. Maybe @amirm can find a recent production sample to test again.