I'm by no means an amplifier designer but I've measured a few and repaired a couple. I suspect the key here could be the power supply. AHB2? SMPS. This amp? External DC SMPS. Everything else with "ugly" noise floors? Internal wire wound transformers and bridge rectifiers aka linear power supplies.
Yes, credit to those who have, you can make ultra quiet amps with big iron supplies but it seems to me it might just be easier to get the power supply that's spraying magnetic fields all over the place away from the audio circuits or use one that doesn't.
Yes, credit to those who have, you can make ultra quiet amps with big iron supplies but it seems to me it might just be easier to get the power supply that's spraying magnetic fields all over the place away from the audio circuits or use one that doesn't.